I have a lawn much like the pics Herler put up. Lots of trees and obstacles and thin/bare turf in many areas in my case. By the time I blow the leaves from the beds and edges and around obstacles, they're really thick on the turf areas. There are rocks and stumps too which can't be seen....just not practical or safe to try to mulch them. Add in a climate with a typically wet fall (often wetter than spring), heavy dew at night and short days, the leaves never really dry out. Mulching wet leaves results in something very similar to wet cardboard. The later it gets in the season the more likely the leaves are to be wet and matted and to stay that way....probably not something that's as much of an issue in Texas.