Once, pretty much, here. Yes, I'll do "extra" work like doing traps on a separate day sometimes, or doing extra hamstring work just because I feel like it, but generally speaking the major back, chest and leg workouts kick my ass really bad no matter what I'm taking.
Recovery is little-understood by many athletes; obviously training for sports may involve higher volumes, daily workouts (swimming, running, skating, rowing), etc.
But ya can't exactly do that with squats, now can you?