I keep the same boot camp series of exercises for 4-6 weeks (we meet 1x/week). This allows the students to learn and master the exercises before moving on to something different. My students LOVE this, because they can see and feel their improvement as their bodies learn and adjust to the exercises. The more complex boot camps stay around for 6 weeks, the boot camps containing more basic elements stay for 4 weeks. This creates a great balance between allowing students to achieve a level of comfort and confidence and presenting them with new challenges to prevent boredom.