Where do you get your grain from? Every time I brew with Brewmaster's Warehouse grain, I top 83-90% eff. I don't know if it has to do with their "crush", or if there is more grain than what I ordered. I don't ever weigh the grains from those guys, so I'm wondering if when I think I'm using say 10 lbs of 2-row, maybe they sent me more like 11 lbs? Either way, it's a nice "problem" to have.
PS...I don't know how much this has to do with my eff., but I typically mash thin-like 1.5 to 1.75 qt/lb. And I only do a single batch sparge.