in my view the 48-hour break is applicable to maximal weight-bearing exercise (high resistance/low reps). this type of exercise strategy presumably creates micro-tears in the muscle fibers resulting in inflammation and repair which needs a couple of days to complete. this strategy is designed for building muscle size. most or all body builders use this strategy and would not typically work the same major muscle groups two days in a row. push-ups and other similar high-rep low-resistance exercise is probably not undergoing the same repair cycle.
is it true that it isn't good to do the same exercise every day to allow muscles to rebuild with a 48-hour break?