eventually, when almost every yard is flat, open and nice, I’ll look into a 52” or 61” and be able to do a few more a day because of the increased efficiency. But, when starting out and before ones route has been pruned and refined I think I will choose the 36” deck every time. At least in my hood when starting and almost every account should be taken that comes ones way.
Ran out of time to edit my earlier post but was gonna say, for around here and it may be the same there, there's plenty of yards to suit any size machine. It just comes down to what a person wants to target. My niche is smaller lawns I can stack up and really don't have a burning need for anything larger than a 36". My buddy likes bigger yards/bigger machines and barely uses anything other than a 60".