i do pshabis rule, but for me its 8 BBs. Theres still a bit of room for play with ten x BB IMO. Also depends on the buy in of the sit and go, if its a small one (below $20) then people are gonna call with anything from Q8 suited to AA. If its the ones i play $50 or $100 6max, then your looking at a more AT - AA range, so if your in the SB/BB and you think the time is right, just try and figure out what they have first. If your in early position, hit and hope man.
Cash games leave the table if its costing you, have an hour off, watch a film, spend "quality" time with the woman, come back and go for it again. Na dif it isnt working, log off and "go for it agian" in other ways