Theory of Constraints Handbook - James Cox Iii [155]
The Five-Focusing Steps (5FS)
The concept of the 5FS3 was developed in 1985 just as internal knowledge transfer within Goldratt’s company, Creative Output signaled the emergence of the comprehensive managerial approach of TOC. It is the first time the term constraint had replaced the older concept of a bottleneck.
The importance of the 5FS (Goldratt, 1990b, 7) is that they define the rules for a “well-behaving organization.” The first three steps define the state of the short-term:
1. Identify the system constraints.
2. Decide how to exploit the system’s constraint.
3. Subordinate everything else to the above decision.
The longer-term steps give an umbrella for developing the scheme for growth coupled with stability:
1. Elevate the system’s constraint.
2. Go back to Step 1. Warning: Beware of inertia.
For a better understanding of the DBR methodology and the transition to S-DBR, only the first three steps have a direct impact. Beginning in 1985, the three steps were extensively used to explain DBR thinking—even though the DBR rules preceded the 5FS. The first three steps are prominent in explaining the shift to S-DBR.
The Critical Distinction between Planning and Execution
The Appropriate Rules of Planning
The role of planning is to synchronize the system in a way that would enable achieving its objectives. Many times, the planning affects objectives by identifying what is realistic to achieve and what is not. Planning is viewed as the higher-level decision making, while the execution is viewed as just having to follow the planning.
There are two main difficulties for any kind of planning. One is the internal complexity in synchronizing many different variables. The other is dealing with uncertainty. The main problem in dealing with uncertainty is that planning decisions are made ahead of time and most decisions are converted to specific actions. This time difference between planning and execution allows Murphy to mess things up to a degree that the planning cannot be executed as is. The situation where in the execution phase it seems impossible, or not worthwhile, to follow the planning not only causes problems in achieving the system objectives but also generates tension between the planners and the people in charge of the execution.
Viewing the DBR methodology versus OPT® might shed light on the way TOC treats the planning rules. Later, we will look at the resulting insights regarding the impact of TOC on decision rules in execution.
OPT®4 was all about planning. It planned all the perceived bottlenecks in detail under finite-capacity and then went on planning the rest of the shop floor where all the non-bottlenecks were scheduled under the infinite-capacity assumption in a similar way to MRP. The hidden assumption was that there was no need to make any significant decisions at the execution phase—just follow the schedule. If Murphy messed things up, then running OPT® again was the reasonable option.
DBR is a planning algorithm that is much less detailed than OPT®. Only one constraint is scheduled in detail.5 All the rest of the resources are not given any schedule.6 However, the material release was scheduled in detail with the notion that the schedule for the material release meant: Do not release before!
Our current understanding is that having good planning means that, in most cases, the plan is eventually executed without changes and it draws good performance from the shop floor as a whole. Any instruction that is included in the plan but is not absolutely necessary to be taken at the time of the planning endangers the sustainability of the whole plan. The rules for what should be included in good planning are:
1. Any instruction where any deviation might disrupt achieving the objectives.
2. Such instructions must be protected from Murphy. Buffers have to be included in the plan protecting the ability to carry out the instructions.
3. Nothing else should