I did p90x once for about 70 days and then I caught a stomach virus that knocked be for a loop for a few days and then I got sidetracked.
Yes it works. It works because (a) you are probably going from a sedentary lifestyle to working out hard for 60+ minutes and (b) you have to follow the diet advice for it to work well.
However, even if you did your own workout for 60-80 minutes a day and start to eat right, you'll get in shape and feel better. Just pick something you enjoy and stick with it.
Mismanaging the clock.