I don't have personal experience with "methylstenbolone" (which in scientific studies has shown to be around 2/3 the effectiveness of methyltestosterone) but have run many cycles to include anadrol, dianabol, and a variety of different testosterones, but no longer than 7 weeks.
. 50 mgs is about the max you should take, after that you are wasting it in theory. I usually ran 50 mgs post cycle for 2 weeks, but I also used 5000iu, (1 shot) of HCG. But that was after a relatively strong cycle.
I'm not sure of the testosterone degradation effects of "methylstenbolone" but I would say to be safe at least 50 mgs for a week or two.