Theory of Constraints (TOC) in a Nutshell (remastered)

Computer simulation of tensions - can you see the constraint?

Theory of Constraints (TOC) in a Nutshell (remastered)

May 4, 2025

Over the past years, I’ve received increasing interest in a simple question: “What is this thing you call TOC?” At the same time, I’ve also heard more feedback like: “You post so much high-quality content - please summarize it!”

So here it is: a clear and concise summary of last year's posts in the “TOC in a Nutshell” series.

Part I – The Constraint Is a Highlander

First, here is a quick definition: TOC stands for the Theory of Constraints, a management paradigm introduced in 1984 by Eliyahu M. Goldratt. At its core is a deceptively simple insight:

Every stable, complex system has one - and only one - constraint (bottleneck) at any given time.

That one constraint governs the entire system’s output and growth. Identifying and managing it is the key to unlocking performance.

Let’s take a car: complex, with many subsystems. Still, you usually know it works and what’s limiting its speed - perhaps fuel flow, engine output, or wind resistance. The same is true of an airport: it is complex, but the runway is often the constraint.

Why is this important?

• No constraint = uncontrolled growth → instability or explosion
• Multiple constraints = oscillation → chaos
• One constraint = stability and controllability → more efficient than the other two cases - so this will win over time

Hence, “There can only be one” (yes, like a Highlander). That’s the first principle of TOC.

So, what do you actually do with the information that there is just one constraint?

Part II – Focus: The Five Focusing Steps

TOC provides a straightforward roadmap: the Five Focusing Steps. Think of this as your guide to systematically improving any system, without guesswork or unnecessary effort.

🔁 The Five Focusing Steps

1. Identify the constraint: Where is the constraint that limits performance and growth? What is holding us back right now?
2. Exploit the constraint: Make the most of the constraint’s existing capacity. Optimize current processes, ensure quality before the constraint, and remove waste. Often, small tweaks here lead to big gains.
3. Subordinate everything else: Align all other activities to support the constraint. Prioritize so that the constraint is never overloaded or underloaded. Avoid optimizing non-constraints - they won’t improve overall performance.
4. Elevate the constraint: If the constraint still limits performance after exploitation and subordination, increase its capacity. This might involve hiring, purchasing equipment, or redesigning processes.
5. Repeat the process: Once the constraint is broken, another one will emerge. Start again from step 1. TOC is not a one-time fix - it’s a continuous improvement cycle.

🛑 Important note from experience: Many teams want to jump straight to step 4 - buying equipment, adding headcount, or launching major change initiatives. But unless you've done steps 2 through 3, it's often a waste of time and money and makes it even harder to improve afterward.

🛑 Important note from experience: Before step 4, think about where the next constraint will occur and prepare, because the priorities are now shifting. A constraint shift is a wonderful situation - with a lot of energy - but be aware that it changes everything.

🧠 Types of Constraints

Constraints can take different forms:

• Physical constraints – Machines, equipment, labor, space.
• Virtual constraints – Knowledge gaps, lack of collaboration, poor alignment. Often, you need these in very short, special phases of a project, at the beginning or in the integration phase.
• Policy or rule constraints – Legal limits, company policies, outdated procedures. These generate bottlenecks in places where you don't want them and are often easy to change, with a huge impact.
• Decision/communication constraints – Misalignment, unclear authority, bottlenecks in decision-making.

And they can appear anywhere - in your team, across departments, or even outside your company.

⚠️ Often the constraint is hidden. If it were easy to spot, you'd have solved it already.

So it's quite a lot of fun chasing the constraint!

Part III – Constraints are often typical

People frequently ask:

“Can you give me examples of real constraints in companies?”

Absolutely. But remember: the constraint always depends on your goal and your system boundary.

Overview of typical business situations and their constraints

For this section, let’s assume the goal is: “Make more money - now and in the future.” And the system is: the entire company.

Here are real-world examples by industry or function:

🏭 Production of simple parts

Constraint: Longest cycle time or the station with the lowest capacity

Example: Heat treatment oven or extrusion press

🧴 Sensory-quality products (e.g., olive oil, fragrances)

Constraint: Ability to distinguish fine quality differences

Example: Expert testers, sommeliers

🚗 Make-to-Order manufacturing (e.g., cars, phones)

Constraint: The final assembly or integration point

Example: “Marriage” station in car production

🧪 Complex/customized processing (e.g., pharma)

Constraint: Scarce specialist skills or flexible job release

Example: Trained lab staff or advanced machines

🛠 Engineering-to-Order (e.g., plant design)

Constraint: Senior engineers with deep process knowledge

Example: System engineers or process experts

📱 Product development (e.g., IT, components)

Constraint: Industrialization or mass-production readiness

Example: Industrialization engineers, DevOps, or final integration testing

💼 Services (e.g., consulting, implementation)

Constraint: Go-live phase or initial customer onboarding

Example: Hypercare or solution engineers

💡 Agile multi-project environments

Constraint: Upfront idea/design clarity

Example: Business analysts, architects

🌐 Platform businesses (e.g., apps, APIs)

Constraint: Core architecture design

Example: System design or core service stability

🎯 The key: Always define the goal and scope the system before looking for the constraint.

You probably know your constraint now, but how do you implement a constraint management solution?

Part IV – Projects vs. Production: Two Different Animals

A lot of confusion in the business world - especially around Agile, Lean, or traditional project management - comes from not recognizing a fundamental TOC distinction:

Projects and production follow different rules.

The key difference? The ratio between touch time (actively working) and lead time (total duration).

🏭 Production = Low Touch Time

• Many small, loosely connected jobs
• Work is flexible and queue-based
• Touch Time << 20% of Lead Time!
• Constraints lie in the value stream (e.g., machines or queues)
• Control method: Drum-Buffer-Rope

📅 Projects = High Touch Time

• Complex, risky, interdependent tasks
• Fixed sequences with strong dependencies
• Work packages can't easily be reordered
• The constraint is the critical chain of work packages, and the Touch Time on the Critical Chain is nearly 80-90% of the Lead Time!
• Control method: Critical Chain Project Management (CCPM)

Shared Principles:

• Due dates are constraint-driven
• Priorities are based on buffer health
• Corrective action starts in the “red zone”

🧩 Most Agile methods use production-style controls. But most businesses depend on projects. That mismatch creates real risk.

Now that you know about projects and production, you'll see them everywhere and very often at the same time - how can this be?

Part V – Yin and Yang: The Hybrid Reality

In practice, every company is a mix of projects and production. Recognizing that helps you avoid applying the wrong control logic to the wrong type of work.

A topology of different blends of production and projects

🤔 What happens if you mismatch?

• Use project controls for production → It works, but you pay with unnecessary planning overhead.
• Use production controls for projects → Simpler, but you pay with dramatically longer lead times - a serious risk in time-sensitive markets.

The trick is knowing what kind of work you’re dealing with and choosing the right TOC control logic accordingly.

🗺 Tip: Map your organization’s workflow types. Understand where you have production flows, project structures, or a combination of both.

But now I assume you want to start implementing this. Let's go!

Part VI – Implementing TOC: Start with the Constraint

So, how do you begin applying TOC in real life?

Start with one simple truth:

The first constraint is often management’s awareness and capacity.

If you're always firefighting or struggling with overload, TOC can help - but only if you and your team can create the breathing room to implement it.

The two typical ways to implement TOC work management

📋 Full Implementation Pattern

1. Emergency WIP Relief – Pause 50–75% (some do even 90%) of ongoing work to regain focus and restore flow.
2. Reestablish Full Kit – Ensure all necessary inputs are ready before restarting critical projects.
3. Prepare TOC Control – Map all work, identify constraints, stagger launches, train teams, and set up buffer indicators.
4. Activate TOC Control – Use operational signals to drive daily decisions. Focus on red tasks. Obey priorities.
5. Drive Improvement – Use buffer consumption patterns to identify root causes and continuously improve.

⚡ Shortcut for Smaller or Pressured Teams

1. Analyze workload vs. team capacity; stagger accordingly
2. Turn on TOC control to generate actionable signals
3. Reestablish preparation for critical tasks
4. Use expediting data to drive continuous improvement

Final Words – From Theory to Impact (that would have been a better name)

That was the Theory of Constraints in a Nutshell - a powerful lens for making sense of complexity, improving performance, and getting real results without burning out your team.

You don’t need to optimize everything - just the constraint. That’s where the magic happens.

If something’s unclear or you'd like to dive deeper, I welcome your questions and comments.

We even founded a community (The DolphinUniverse) around these ideas to reach "hyper-productivity!" You get over 1.5GB of articles, videos, books, and even Excel tools to start. Furthermore, you get three courses to guide you through implementation in your team or project. And a lot of TOC experts are just waiting to answer your questions.

It's free and open to all who want to grow:

📁 Go to the DolphinUniverse