Back to Newsletter

The Basis of TOC Excellence: Your Assumptions

Nov 10, 2023

5 minute read...

A good portion of Jenrada’s audience is TOC practitioners. Which makes sense. That's where I've spent much of my career. In fact, I chose to focus on assumption hacking largely because of my experience with TOC and the many years of guidance received directly from Dr. Eli Goldratt. I believe the assumptions we hold are fundamental to the results we get (or don’t get). 

Heres what Eli himself had to say on the subject:



If the challenging of basic assumptions really are essential to breakthrough (and I think they are), then it follows that becoming adept at hacking your assumptions will make you a much better TOC practitioner.

Here are three ways:

Hacking the fundamental assumptions of a generic TOC solution

Every TOC solution is built on basic assumptions about the environment of the problem it is intended to solve. An Assumption Hacker will diligently check to see if those basic assumptions apply before taking the standard implementation steps.  

For example, the first step most practitioners take when implementing Drum Buffer Rope is to cut the current production lead time in half. The shorter production lead time is then subtracted from the due date to determine when work should begin on the job. Most of the time, this leads to a significant improvement in flow and results. Examples include faster job completion, more jobs completed, and more jobs delivered on time - without increasing operating expenses. This is the case as long as two fundamental assumptions about the starting condition of the operation are true: 

  • The touch time (the longest chain of processing time) is a mere fraction (less than 10%) of the current production lead time (that is the time allotted from authorizing the work to begin till the job is completed and ready to be shipped or delivered). 
  • The operation is flooded with too much work in process.

Cutting the lead time in this case simply removes excessive wait time. The result is that jobs waste less time waiting for the next resource to perform its part of the process. However, if the touch time is significant relative to the production lead time, then we run the risk of truly not having enough time to perform the process. Chaos, rather than better flow, can become the result.



The good news is that it is not difficult to rapidly check the validity of both assumptions in the implementation’s environment, before proceeding with that first powerful set of actions.

Quick tip: Be clear on the fundamental assumptions made about each element of the change you are implementing and check their validity before you start. When you find reality to be different than what the solution assumes, determine the adjustment that should be made and test it. 

Learning why something isn’t going as expected

 Any implementation of a change is accompanied by instances where what we expected is different from what reality presents to us. TOC implementations are no different. Sometimes we get a different outcome because the solution isn’t the best fit for the reality of that environment. In other words, a fundamental assumption of the solution is invalid for that environment.

Often, we get a different outcome because of the actions taken, not because the solution is wrong. 

Results come from actions which come from decisions which come from assumptions. 

Sometimes a different outcome is due to the assumption that drove the action.

And sometimes it's the result of failing to take the intended action (in full or at all).

Our human tendency or instinct is to jump to the conclusion that there is something wrong with the solution itself. That the solution just “doesn’t work”. This is very often a faulty conclusion though, one that has borne out many times over my 30+ years in TOC. More often than not, the problem is not with the solution but is instead a result of not following the recipe. Before you say a solution doesn’t work, you have to ask yourself: “did we actually follow the protocol?” 

So here’s what you can do instead. When you face an outcome that you didn’t expect:

Check first whether the action taken was in fact the action that was intended. If not, then gain an understanding of what blocked the action from being taken in full and as designed. It may be as simple as a misunderstanding. It may be an obstacle that was not considered and that needs to be removed. For example, taking the correct action may have been perceived to be in conflict with a performance measure. For a further explanation on “following the recipe”, check out this video.

Conversely, if the action was taken as intended, then surface your assumptions about the link between the action and the result. Why did you believe the action would lead to the expected result? Asking this question will help uncover the flaw that led to the unpredicted result and give you the ability to course correct. 

An excellent hack for uncovering the flawed assumption that led to an unexpected result is the 8-step Mystery Analysis. Want to learn how to use a mystery analysis for uncovering your own flawed assumptions? Let me know here if you'd be interested in a free webinar by clicking here.


Outline of the 8-step Mystery Analysis.


Get better at using the TOC Thinking Processes

The TOC Thinking Processes were developed in order to help us do three things:

  1. to better understand the situation we are in so that we can answer the question “what to change?”
  2. to help us better clarify the future we want to create as we answer the question “to what to change?” 
  3. and to help us get better collaboration with those who need to participate in creating that future as we answer the question “how to cause the change?”

The first step in using any of the TOC Thinking Processes is to diagram what we are thinking. That helps us clarify and communicate what’s in our mind. Unfortunately, too many users of the Thinking Processes stop at the point of reading back what they’ve diagrammed to themselves and/or others. Additionally, many people will stop making corrections once the answer to the question “does it make sense” becomes “yes”. 

While what makes sense may reflect our intuition, it may not reflect  reality. What makes sense to you as an individual is based on the assumptions you’ve made and the experiences you’ve had in life. And this is why Goldratt developed a set of questions (categories of legitimate reservation – see note below) to help us surface and challenge the assumptions we’ve made so that we have a better chance of making decisions grounded in what’s real.


Every arrow in the diagrams you create represents an assumption.


If you are a practitioner of the TOC Thinking Processes, remember that every arrow in the diagrams you create represents an assumption – the unstated reason why the effect comes from your speculated cause.  And until you make it a habit to surface and challenge those assumptions, you are leaving most of the value of using those tools on the table.

Til next time,



Note: If you’re wanting to improve your use of the Thinking Processes and the assumptions you make along the way, you should check out Jenrada’s forthcoming Assumption Hacking Essentials Course where we make the categories of legitimate reservation more user-friendly. You can also purchase JonahLisa's book Thinking for Change, a step-by-step guideline for each of the five thinking process application tools.



Whenever you're ready, here are a couple of ways I can help you:

  • Assumption Hacking Essentials. Dr. Eliyahu Goldratt said in his forward to The Goal, “The challenging of basic assumptions is essential to breakthroughs.” In this digital course, I'll take you through a five step process for challenging those basic assumptions and creating breakthrough in the process. Join the waitlist and get notified when the course is released.
  • Jenrada Programs. Customized workshops and longer engagements to help you create an organization of aligned problem solvers delivering extraordinary results. Complete this form,  send me an email, or schedule a discovery call. 


Your Weekly AHA!

Every week, receive one actionable tip from JonahLisa to help you create breakthrough in your business and life.

We hate SPAM. We will never sell your information, for any reason.