My 2 cents
I don't like 1 men crew for the following reasons.
1. what if one person calls of sick which happens all the time in the lawn care industry. If you only have one man to the truck you miss a whole day or two of mowing. If you have a two man crew you can just send the one out and get the job done.
2. Morale will be low in the company. When you mow by yourself which I did for years you just don't have the same spunk as you do if you have a partner. You skip a spot in the backyard, you don't edge every week,just the little things you start slacking on because your trying to speed through everything to get it done.
I think if you have a strong one man worker throw him out their , but I wouldn't make all my crews one man.