This is one of the great things about the Pilates method: The levels and layers of exercises allow you to go wherever your body is at, working in a place that is challenging yet doable for you.
Unlike other training methods, Pilates doesn’t simply add reps or weights to progress your body through a physical fitness program. As you advance you are required to do more complicated exercises with a variety of different elements. You might use more or less spring, alter speed, change your plane in space, increase range of motion, or limit surface stability to challenge your body’s mastery of different principles.
The levels are designed to develop your body slowly and safely, allowing you to layer on skills in a way that feels satisfying rather than frustrating.