Bryan,
While this comment is not exactly on point I have discovered through trial and error a method you all probably already have learned. I am just a little slow on the uptake sometimes.
I have my three acres divided into three main areas and Yarbo must recharge at least one time per area. I mow at 2.7 inches and medium speed (which seems like a snails pace). Each time I mow I set the mowing angle at 90 degrees from the previous time mowing and I mow very frequently, about every three days. It seems that Yarbo is always running somewhere but, hey, it is a robot and I kind of like to watch it, especially at night.
My lawn looks like it was mowed professionally — not even a little rough. I am extremely pleased with my Yarbo and my neighbors are all envious, which is icing on the cake.