Scheduling | By Mark Woeppel | Read time minutes
In spite of the fact that project task durations are often conservatively estimated to begin with, the presence of certain behaviours can cause them to increase. Critical Chain Project Management and project scheduling eliminates these behaviours and reduces project lead times.
Four behaviours make project durations longer than necessary.
Once the people doing the work have conservatively estimated their tasks, the estimates are then passed through several layers of management where they are increased. Because managers feel they must protect their own performance, in many organisations task estimates are not treated as "estimates," they are treated as "commitments." People don't want to be late on commitments, thus, they "pad" their estimates of how long a given task will take.
"Student Syndrome" is a term that pertains to the psychology of procrastinating, something students are particularly prone to do. The analogy is to students who are going to take a test. When do they study for it? The night before! Why? Because they have much more important things to do! Often in projects, people start too late, using their safety time to work on other things, thinking they still have enough time to complete the task on time. After they begin the task, they run into problems, causing it to take longer than the original padded estimate. The Student Syndrome causes longer durations because some of the time needed to complete a task is lost when it's started too late or even when it's started "just in time." Then, Murphy causes the task to take even longer.
This "Murphy" is really two things: common cause process variation and special cause process variation. The two types of variation are not differentiated in the text, but in the implementation, must be treated differently. Common cause variation can be predicted and managed using the CCPM approach. Special cause variation must be treated separately in a risk analysis process.
Multitasking occurs when an individual is working on more than one task at the same time. There are two kinds of multitasking: good and bad. Good multitasking is moving two or more tasks along together smoothly, such as catching up on customer calls while heading to a meeting. On the other hand, bad multitasking is anything but smooth. It's the dropping of work on one task before it is finished in order to start another, only to stop and begin yet another task or go back to a previous task. All too often, people aren't able to complete a task without getting pulled off onto something else, so "task time" grows each time a change is necessary. Goldratt wants you to see that the majority of task completion time is not used for the actual work, but is waiting or queue time. Tasks ready to be worked on cannot be worked on because there is no available resource. If the estimates are too long, during execution the actual time will grow even longer! No wonder projects consistently finish late and over budget.
Parkinson's Law states the amount of work rises to fill the time available to complete it. In projects, it means that early task completions are never reported. Resources will continue to work on "improving" their task or will simply find something else to do until the due date of that task. In any case, the result to the project is that only the late finishes are recognised, so the only way a project timeline moves is out.
These two behaviours, Student Syndrome and multitasking, have the same root cause, the lack of clear priorities. Student Syndrome occurs when you believe the real due date is distant, relative to the amount of time needed to complete the task, while bad multitasking is caused by not recognising the real priority of tasks until they become late relative to the "need by" date.
Why Do Projects Take So Long?
- We add too much time to the original plan. We allow x amount of time, so it takes x amount of time.
- Our resources multitask, adding unnecessary work (additional set-ups) to the project.
- Student Syndrome causes us to waste whatever buffer we did have, adding more time to our already generous estimates.
- Parkinson's Law blocks us from taking advantage of any favourable variation (tasks finishing early) the project experiences.
Implications for Project Management
Critical chain seeks to reduce/eliminate these behaviours, and therefore they are not planned for in the project. We can overcome deliberate padding, student syndrome, bad multitasking and Parkinson's Law through better management and communication.
After removing the safety time from these tasks, the critical path is shortened significantly. These are the reasons that projects managed using the critical chain method consistently finish in less time than projects that do not use this approach.
For his entire career Mark Woeppel has been challenging the status quo in organisations, helping to make changes that matter. He is founder and president of Pinnacle Strategies, a consulting firm delivering Critical Chain CCPM implementation and training.