Q. If I do push-ups and pull-ups before bed, will that maximize my gains?
A. NO. A common weight lifting mantra is "the build comes in the recovery." When you lift weights, you create microtears in the muscle fibers, which over a period of days slowly recovery and rebuild slightly stronger (and larger) than before. If you just worked really hard on a chest and back workout, you could actually "shred" the recovering muscles and minimize your gains by even doing a handful of reps later in the day. That's why programs like p90x have rest days and recovery weeks built into them, and why you don't work the same muscle group two days in a row.