Honestly, camp isn't nearly what it used to be. The limitations on impact, banning of junk like Oklahoma drill, length, etc, have de-toothed it significantly. It isn't like the old days where the 2 a days had guys re-tapping raw skin and doing 2 full run-throughs of full contact and high exertion. The off season for players is also far more active, and you don't need to do nearly as much reconditioning.
Now that said you still have to be smart, not like chris jones blowing out a half dozen guys ACLs per day for the first few days.
Frankly, I don't care if the vets sit half the day or every other day or what ever they need to. As long as they can be ready to play 1q of the first preseason game, 1 half of the 2nd, and be at full pop for the first regular season week. Aside from injuries in camp and guys coming back from injuries, if a vet can't consistently do that, they are probably done anyway.