I just finished 5 sessions of SBRT every other day for 10 days (MWFMW) at the Mayo in Rochester and was pleased with the result. I hesitate to try to paraphrase what my doctor told me about shorter timeframes. But it was something to the effect that prostate cancer responds better to higher doses over shorter periods. Perhaps someone can state that better or provide a better explanation.
Regardless though, the message I got from my doctor was that short course and long course radiation are equally effective. It might come down to what you want to do or the time you have. I had to drive an hour for each session so that definitely factored into my decision.
Didn't feel anything during the sessions. Started to get some symptoms the day it ended. A week after, feeling the need to pee more, but that is about it and to be expected and certainly not terrible.
The worse part for me was the anticipation of getting the SpaceOAR gel injected and I dreaded it for weeks. But that turned out to be nothing to worry about, they give you moderate sedation, and you won't remember or feel a thing (other than getting strapped into the stirrups).
I heard that exercising right before radiation makes it more effective as it oxygenates the tumor. I parked far away and ran for 15-20 minutes before each session. But you could also walk briskly or do the steps in the hospital too and probably get the same effect. I also adopted a FODMOP diet about a week before I started sessions. You don't want to be gassy or have things moving around down there. There was no need for pre-session enemas or anything for me.
Good luck.