Curiious about lawn aerating, for a few things or reasons. In regards to how shallow drain pipe may have to be in a few cases, how deep do your tines typically penetrate? If you run into a rocky lawn, do you have a gracious way of backing out of the project? Do you tape flyers on houses and aerate for anyone and everyone who calls, or do you prefer to wait for the soil to attain a certain firmness first. How many passes over the same spot can you do with your equipment feasibly? Full coverage twice? Three times? Because I've never felt that once would be optimum. Do you even like aerating? Do you do it more because its essential and you must do it, or is it a service that you find worthwhile even from a money earning point of view?