Every single one of my lawns is below 7500 sq ft with most of them in the 5K range and I have yet to find an efficient commercial set up. Most of them are gated, and they usually all have obstacles. Nonetheless, a big mower just won't work. A 36 is even difficult to maneuver just because of the size of the yards and obstacles. A 21 obviously works but gets the job done slow. Residential equipment has done fine but isn't holding up and isn't the fastest and doesn't leave a great cut on thicker grass. What would you guys use to get the job done as quick as you can while leaving the yard looking as nice as possible? Remember, every one of my lawns really are that small. It's just the size of the lots in all the neighborhoods near me. Only a couple lawns don't have gates, and even then they are not large wide open fields. Am I stuck using a 21? Thanks for the help!