The problem is the simple geometry of the situation... my tractor vs. their land. Admittedly, my tractor is probably too big (i.e., too long) for most of the "back yard" work I find myself doing.

One second my rake is in the ground doing fine and the next minute it is all plugged up with roots & rocks or up in the air. I have to actively monitor it and keep it clear. This is not just a case of setting proper depth once, being able to forget about it... and allow it to adjust itself to keep that depth. This is a problem of making almost constant adjustments to follow the contour of some of these relatively small, uneven, under-reconstruction back yards.
Remember... half or more of the reason I am there is to straighten out these silly yards... and usually that means I have been digging and/or placing material... so don't expect them to be uniform enough in the initial stages to behave nicely as I'm trying to do the smoothing out work!
Dougster