Any kind of movement or exercise is better than doing nothing! There is basically no lower limit when it comes to getting results from exercise. It takes more effort to build strength and other qualities, and less effort to maintain them. This means that even as returns diminish, or if you have to do abbreviated routines, you can still have efficient workouts. Programs that use short, intense, and infrequent workouts can provide reasonable, long term results. As long as the program is followed consistently and progressed smartly, there will be improvements.