To add to this, I'm going to do some further testing on the weekends in the neighborhood with the neighbor lawns over the next two weeks between the 22" and the 30". I suspect the 36 > Faster then the 30 on very open lawns. The 30 > 36 on small tight lawns with lot's of obstacles, corners, fence lines, flower beds, etc. And I suspect both the 36 and 30 > the 22" on all lawns. I'm going to start timing each and every one of the neighbors lawns this week. Funny thing, my neighbor must have got tired of seeing me mow all the neighbors lawns in the neighborhood. I seen he painted an old wooden sign and put on his privacy fence that says "Low Cost Lawn Care 512-xxx-xxx.) Now I'm thinking about putting a sign in the yard or on my privacy fence that says "Expensive High Quality Lawn Care 512-xxx-xxxx.