Good article in this month's Military Review:


Afternoon PT: Key for an Army Flextime Battle Rhythm
Captain Mark Van Horn, U.S. Army

With great stress, commanders are seeking better ways to help. They
encourage Soldiers to spend time with their loved ones, but they must bal-
ance the requirements of reintegration with compressed pre-deployment
training. This is a notoriously tight rope to walk. Morning physical training
(PT) determines when Soldiers report for work. Close of business comes
when—as a member of a team, squad, or platoon—all the work is finished.
There is a more productive way to approach this routine and preserve the
cohesion of the unit: make PT an afternoon ritual. If commanders simply
shift the physical training time from morning to afternoon and empower
company-grade leaders to send Soldiers home when the work is done, the
Army will have a flextime schedule that works with regimentation. Soldiers
will get the opportunity to spend more time with their families, pursue
personal interests, and generally improve their quality of life, with reduced
stress, less commute times, and better health.
.....
Convincing case.

I don't see the current crop of CSM's ever allowing it - it just isn't done that way!