The trouble with Process Maturity Assessments is well-captured by Alberto Manuel on his blog:
Do you believe it?s worth to start a change program because you have a process at level 3 maturity stage when a level 5 process, customer critical is the first candidate? What if all processes equalize at level 5 (like human assessment methods that after 3 years of implementation 80% of employees reach the top of the scale).
Interesting points... I think he identifies precisely how maturity models (of any type) can be misused.? The goal isn't to get to level 5, in my opinion.? The goal is to be honest with yourself about where your process is at - and be able to ask yourself whether a particular level of maturity makes sense for the process in question. ?
As a wise person once said, if you have 10 major corporate processes you are looking at, should you invest your budget for process improvement equally among the 10? or should you invest it disproportionately toward the major processes with the most room for improvement?
A second problem is whether the maturity models ask the right questions to provide useful maturity differentiation between processes.? In other words, are the differences actually moving the needle on how processes perform, or are they just easy things to check off on a corporate compliance checklist?? Only the former has value.
Still, I always felt that it is a Good Thing to have a way to be honest with yourself and your organization about process. Process Maturity is one attempt to provide that visibility or honesty, however flawed.