In Pilates, we are taught to leave the injury alone and work the rest of the body.

The one thing about Pilates that is different from many exercise regimes, is that it works the WHOLE body! From the top of your head, to your tippy toes. It is also set apart from physical therapy, as it works your whole body regardless of injury or aliment. A fellow instructor from South America, who also has a background in physical therapy, mentioned many years ago about a study that was conducted in Brazil. They tested people with injuries and put them into categories:
1. they did nothing about their injury
2. they did physical therapy
3. they did Pilates
If they did nothing about their injury, as you can imagine, there was no change in improvement. If they did physical therapy for their injury, they jumped into the 70 percentile of improvement. If they did Pilates, they jumped into the 90 percentile of improvement. In Pilates, we are taught to leave the injury alone and work the rest of the body. At the ending of a session, you strengthen the injury.
Generally, a private session consists of Reformer work, Mat work, and then body specific exercises. Often times they are done on other apparatus: Cadillac, Barrels, Chairs, etc. Sometimes they are just an exercise the teacher decided to make up for the specific body. This is the time, if you were strengthening an injury, you would give that specific exercise.
If a person is more advanced, you may just work on one specific apparatus, like the Reformer or the Cadillac. The whole session can be done working on advancing the body with the apparatus that will help the body into the work. Sessions are generally 50-60 minutes, depending on your studio. If you happen to be working out in a certifying studio, you may get a little extra time working with an apprentice. Working on you Mat, as it doesn't require any apparatus, is a great way to help strengthen your body and practice for your private sessions!
Your workout and progress will depend greatly on you! Do you want to improve your general body awareness? Or do you just want "a good workout"? Either way, you'll find both. It's like "real life", you will advance based on your willingness. "Advanced" doesn't necessarily mean doing all the "bells and whistles". Many people have the misconception it's being able to do all the exercises. How do you get there? Understanding your body more and applying it to your workout. You can do Footwork, a Beginner exercise, and be advanced in the execution. It's not just about adding more exercises and doing them fast. Again, it's like "real life". Just because you have more work at your job, doesn't mean you're better at the execution, unless you've learned to do it with style and finesse in a short period of time.
I hope this article gives you a little insight on Pilates. Fell free to ask questions!
Love, Light and Blessings,
Julia