Care to elaborate on that whole concept with the 21's? I would be interested to hear the reasoning behind that. Would your customers be resentful if you finished their lawns in 5 minutes? Or do they percieve larger mowers as being damaging to turf? Are operating costs less for your labor than for $6000-7000 mowers? Are you trying to keep employees busy so they are there and at your disposal for large landscape jobs?
Obviously you do not know what a 1000-2000 sq ft lawn with a fence around the backyard is you can do it as fast or faster with a 21 than a 36. I have both and yes you can use both on them but on majority of them the 36 is actually a pain they are so small. I am as lazy as anyone, when I mowed I rode whenever possible but with the lawns Jim mows the 21 is the clear choice. By the way I have found the smaller yards are the most profitable. The market does not let you double your charge for double the double the lot or the time spent on larger lots