Two things I love have something common--with both food and Pilates, quality trumps quantity. Six to eight carefully executed repetitions of most Pilates mat exercises are enough to build strength over time. When you add resistance on the apparatus, even fewer repetitions may be necessary. Pilates isn't a quick fix because you need to practice regularly to get results, but you don't need to devote hours a day to get in shape using the Pilates method. As you get stronger, you increase the intensity and number of exercises rather than bumping up the repetitions. As a result you can continue to devote the same amount of time to Pilates and still get a progressively tougher workout.
I teach Pilates in a studio behind my home in the Rockridge neighborhood of Oakland, California.