We run a three man team most days using one man on trimmer, two on 21" push mowers. The trimmer man will jump on a third 21" push when trimming is complete. We can manage over 30 lawns a day usually in about 6 and a half hours (these are regular and large lawns in urban environments). A two man team can manage 20, a four can do 40, five cannot do 50. I find the three man team includes no standing around by any one team member. A four man team usually has some down time on each job by at least one team member.
I hope this helps,