Many people do this. I have found for me I like to set up a workout, and stick with it till progress stops. As long as I am making gains, whether in strength, reps, or rest times(really the 3 ways gains are made) for 2-3 weeks, then I have "peaked" on this workout and time to change things.
Much research I have read seems to quantify this approach. The body will adapt to increasingly heavier loads this way, and may indicate gains. Anyway, we are all different, and find out what works for you.