^To piggyback on that (yes, piggyback for those of you playing AOM bingo)
Warmups suck the life out of the entire process.
Students - It just means they are going too long between flights. Primary VT students need to fly about three times a week to maintain decent proficiency (mileage may vary, obviously). While your buddy is flying his warmup flight, you are sitting on your ass because you didn't get scheduled that day and then you fall into...wait....here it comes....the warmup window. It is a vicious circle.
Squadron - Warmups are not an advancing X, and therefore are pointless as far as the squadron is concerned. Ops cares about just a few bottom line numbers, and advancing X's is big on that list.
Instructors - Get worn out by warmups due to the same reason - the students usually suck at least a little, and the stud doesn't advance, so the IP just has to fly the X on the next flight.
If you put too many students in training (I don't remember what the magic number is, but somewhere around >130), then there aren't enough lines to schedule them all and you start putting studs in the warmup window, especially when you consider weather, aircraft, etc, etc.
Depending on where the rat is in the snake (usually the formation block is a big one in the VT squadrons), you may be stroking and then just hit a brick wall waiting for your turn up to bat.
I suspect that NASC is just getting sick and tired of all the A pool buffoonery, and is trying to get guys moving so that they can go make someone else's life miserable.