Changes in design can either be tightly or loosely coupled to changes in scope. In general, you can’t change one without changing the other. This is how I think of design and scope. Others think of them differently.
Few people intentionally change the scope of a project. Design changes, however, are usually intentional and frequent. They are also usually small relative to the overall project design so their effect on scope and progress can go unnoticed.
Nonetheless, small design changes are additive. Accumulate enough of them and it becomes apparent that scope has been affected. Few people recognize what has happened until it’s too late. A successive string of “little UI tweaks,” a “simple” addition to handle another file format that turned out to be not-so-simple to implement, a feature request slipped in by a senior executive to please a super important client – changes like this incrementally and adversely impact the delivery team’s performance.
Scope changes primarily impact the amount of Work to Do (Figure 1). Of course, Scope changes impact other parts of the system, too. The extent depends on the size of the Scope change and how management responds to the change in Scope. Do they push out the Deadline? Do they Hire Talent?
The effect of Design Changes on the system are more immediate and significant. Progress slows down while the system works to understand and respond to the Design Changes. As with Scope, the effect will depend on the extent of the Design Changes introduced into the system. The amount of Work to Do will increase. The development team will need to switch focus to study the changes (Task Switching. ) If other teams are dependent on completion of prior work or are waiting for the new changes, Overlap and Concurrence will increase. To incorporate the changes mid-project, there will likely be Technical Debt incurred in order to keep the project on schedule. And if the design impacts work already completed or in progress, there will be an increase in the amount of Rework to Do for the areas impacted by the Design Changes.
Perhaps the most important secondary consequence of uncontrolled design changes is the effect on morale. Development teams love a good challenge and solving problems. But this only has a positive effect on morale if the goal posts don’t change much. If the end is perpetually just over the next hill, morale begins to suffer. This hit to morale usually happens much quicker than most managers realize.
It is better to push off non-critical design changes to a future release. This very act often serves as a clear demonstration to development teams that management is actively working to control scope and can have a positive effect on the team’s morale, even if they are under a heavy workload.