There are many reasons to set a minimum. One that's often overlooked is just the administrative time to manage a customer relationship....communication, invoicing, collection, bookkeeping etc. Generally speaking that's the same whether it be a 1,000 square foot or a 2 acre lawn. Then there's of course the travel time, the time to unload/reload 3 or 4 pieces of equipment. There's a certain minimum level of effort required to mow any lawn. Now if you've got one that's next to another at the same stop, that's where you can start knocking off a little bit. But what if you lose the one next door? Then what? Like I said, my minimum is $40 but I do make rare exceptions...currently two, a $25 that's no more than 1,000 sq feet that's the same stop as two others and a cottage grassy parking area that's is owned by one of those two others about a mile up the road that I bill $30 for. I had more to say, but pizza is ready so figure the rest out yourself, lol.