At work I enjoy sheng brewed 'western style' and 'semi gongfu' in 300ml yixing. Ratios are dependent on the cake potency but puerh is often so flexible I would not stress too much (just don't overbrew #1).
I never brew just one pot of sheng, 2 at very minimum so times for two infusions would be roughly 1m 30s-3m on first, and then 3m-long long time on second. (for two brewer I do not use much leaf at all)
For 4 brews I go roughly 1'st 30s-1m, second can be 20s-2min, 3rd 1-6 mins, 4th long (3-8 grams)
Time ranges are so wide to account for cake potency, compression, and loose leaf sheng. This is constantly being changed though and it will be interesting to see what my reply to this would be in a year when I have drank more puerh (still pretty new to it all).