The 8 man model works out pretty well. Assume a typical appearance is 4 innings to get through the order twice. It leaves just 1 inning to cover per day and 4-5 5 bullpen arms to do it, so there is certainly some chances to play match ups in there, and a cushion to absorb one of the 2 'starters' struggling. You have 41 starts to cover, so the innings total ends up around 150-160 for the season. I would think only typically going more like 60-70 pitches means the one day less recovery is reasonable.