One lineup should be the highest ROI figuring its the best decisions you can make. I think on most slates you can make more then 1 +EV lineup though. Just adding more lineups that will have a lower ROI then your original lineup should be more profitable then just playing 1 lineup at max ROI.
On a night like tonight playing less lineups than last night with a huge slate is the way I do it. Seems to work for me but I dont think anybody has it completely figured out yet.