If its good stuff (which it should be) 25mgs/day is enough to drive my libido through the roof and possibly cut down on some bloat. 50mgs/day is my limit so far anything over that and I don't think I could take it, like mentioned above it would make me too damn horny.
I do know some people that love it at 100mgs/day though. Great libido and keeps them dry.
If you are planning on taking Proviron as an anti estrogen, I would not. From personal experience Proviron is weak at best as far as an anti estrogen. It will dry you out and boost libido, but I would throw in some Arimidex or something. I managed to get gyno sides with just Proviron and no anti estrogen with legit Schering.