It also depends on how fast of a learner you are too. If you submit one review and the mentor has to go over it with you, then turn around and submit another one were the same thing happens, then the mentor will keep you since you are not ready to be on your own. Of course this is not every mentor.
Most of the time my students are done in a week. But I have had some that were around for 2 months. It will depend on you and that mentor. I know I have seen some people complain about the mentor not getting to their reviews fast enough, but you have to remember you are not the only student.
Thank you for the lovely comment on my wall!