i play in two leagues every year...one w 20 and one w 40. they are played very differently, but both work. the one w 40 has 10 total pitching spots to fill and 6 total BN spots, so getting 40 is not a problem. but i have seen managers not get this many due to weather delays and injuries where he couldnt get enough SP in there.
but i feel 20 is too little, as many managers(myself included) are able to stop pitching SP halfway through a week. w 20, if you get 2 good starts early and have active RPs tehn you dont have to pitch over the weekend.
next year i think ill try and push teh 20 league to make it 30. i feel 30 will be a good value