While it might be an exaggeration to call a project plan a battle plan, no project plan is ever perfect or will perfectly encompass the project from beginning to end without the need for changes or updates.
No battle plan ever survives contact with the enemy
Field Marshal Helmuth Karl Bernhard Graf von Moltke
Therefore it is not unusual, even with simple projects to see changes to the timeline. Once theses events start to diverge from the planned schedule, it can be tempting to make a revision. After all, what’s the point in a schedule that doesn’t reflect reality?
Why do we Need a Project Schedule?
Project schedules should serve as a reference for the project team and stakeholders about where their project should be in terms of time, and just as importantly, where the project actually is. They typically take the form of Gantt charts and if needed this can be broken down into several schedules at different detail levels.
Project schedules also form the foundations of a project. Most of the team will have been involved in creating the project schedule at some level and may feel some ownership of it, in contrast to many other project management tools. Project schedules are also widely shared outside of a project team, for example in reporting to management and customers and they will normally be a politically important document (in contrast to perhaps a WBS). This is because they are relatively easy to understand and track one of the key project metrics (time). In short, lots of people will follow and understand the project schedule, and many will have an opinion about it.
Why Shouldn’t you Revise a Project Schedule?
If they are the part of the foundations of a project, it follows that revising project schedules can create uncertainty in the project.
There are now multiple versions of the schedule. Does the team buy-in to the new schedule, was everyone consulted? Did all the stakeholders and suppliers receive a copy? Does the new plan reflect all other minor changes in the project that have taken place since the last edition? Creating, distributing and implementing a new schedule generates additional work for you and the project team and introduces the potential for confusion and disagreement, even if the actual change is minor.
In addition, if a project is behind schedule, creating a new schedule can reduce pressure and motivation to recover once the delayed completion date becomes “part of the plan”.
Finally, teams may delay new tasks or put off planning their own work once they hear that a new project schedule is on the way. This can create an atmosphere of uncertainty in a project and waste time.
When to Revise the Project Schedule
I like to differentiate between updating a project schedule and revising a project schedule. Updating a project schedule should be a regular task during a project that simply tracks progress and task completion. Revising the project schedule should be done as infrequently as possible, in order to simplify the project management.
Before I change a project schedule, I try to consider if it will help the project. Here are three questions to ask yourself to help decide if a revision is needed:
- Has the planned schedule actually changed (what is needed) or is the project just not on schedule (what is being delivered)? Can I reasonably explain the situation with a comment instead of a new schedule? For example, “we are currently two weeks behind schedule.”
- Will I have to update the schedule soon anyway? Can I reasonably delay creating a new project schedule? For example “we will reassess the project schedule in three weeks, once we also have the new delivery dates from our customer.”
- Can the changes to the project be better communicated with an update to another document? For example “now that we have outsourced some of the design work to a supplier, the project network diagram and project activity diagram will be updated. The overall project schedule is unaffected.”
