Reading these last few posts I wonder if we can compare it with doing homework for school. It is the student’s responsibility to do the homework required to pass the test/exam. I do of course realise that fitness for an active duty unit is at a different scale of importance, and effects the unit much more than a school situation where every one is an individual. But I think that conceptually the underlying philosophy with regards to instilling a sense of responsibility is what Ken and IntelTrooper are perhaps alluding to:

My point was that a physical fitness regimen tailored to the individual, along with clear expectations and measurements, can accomplish the same thing without tying up an entire installation for hours on end.
Maybe Entropy has the right idea with a mixed balance, where the occasional organised PT could be structured towards instilling that sense of responsibility and understanding of purpose.
Hmmm, as usual, no silver bullets…