The quote
"One other cause of the problems that seems not to have received much comment is that if most of the people on a project change part way through, through retirement or whatever, key aspects of their approach may get lost too."
I've often thought about this re the military way of everyone changing jobs after 2 or 3 years. (especially officers (read managers))
The first 9 months are spent bringing the individual upto speed on how their new job works, the last 9 months are spent winding down (new posting is being sorted etc) which leaves possibly only 6 months of good honest productive work.
I've no doubt the frequent changes produce a more rounded and experienced individual but do the jobs get done in the most productive way?