One of the hard lessons I've learned in software is that force of will can make any development or management process work for a little over 12 months before the cracks really start to show. By then people (and by people I mean folks who don't think the way I do) have cemented that process in their heads as working and they want to ignore the data that says it doesn't.

If you are up or out as a manager, then any changes you didn't make right at the beginning of your tenure are going to unravel under the watch of your replacement. You not only don't have to reflect on them, but lots of people nominate someone else as the person who needs to fix it/take the blame. If there's a better recipe for willful ignorance, I don't know what it is, and I'm pretty sure I wouldn't want to.