My professional school required 16 hours of psychotherapy prior to sitting for dissertation (or was it for my qual? I can't remember). I ended up getting about 90 hours, and would have done more if I could have afforded it. I admit, I was having some personal problems at the time so I jumped at the excuse to get some professional help, but I also think it really, really helped me be a better therapist.
I also think it behooves students to not skimp on the quality of the therapist they sign up with. Spend a little extra on someone with an ABPP, or with really quality experience working on issues that matter to you. I made the mistake of trying to do my required psychotherapy "on the cheap" and in the end went ahead and got myself an experienced, ABPPed psychologist for the bulk of my therapy. I feel like I really benefitted - I got some resolution for my own personal issues, and I also felt like getting help from really quality therapists helped me to better mold my own professional identity - it's one thing having your academic mentor or supervisor as a model for your professional identity, it's another thing (and an appropriate thing, I think) having your therapist also play that role. Just my two cents.