Grain mill crush speed

So there may not be stupid questions, buy there sure are a lot of inquisitive idiots. This probably falls in that category...

I recently got my own barley crusher. However, I have been less than impressed with it until recently. The thing that made the difference is running my drill slower than full throttle (actually just barely spinning, maybe 150-200 rpm). Since slowing things down I have had much better effeciency.

I only have three batches using the slower milling speed and I am still fairly new to AG so other factors are likely at play. But, I am still a bit worried about the increase in effeciency (~60% to ~83%). I am wondering if I should adjust the gap on my crusher, keep running at the lower speed, or throw caution to the wind and assume my better effeciency is due to me getting more comfortable with AG?

I tightened up my BC a bit from it's factory setting (I turned the dials by 45-90 degrees) and now I happily get 89% efficiency consistently -- and I spin my drill as fast as she can turn. Aside from a fine crush and a fly sparge, another efficiency booster is knowing how much sparge water you need or when to cut off the sparge water and drain the tun dry. If you can completely drain your tun just as you hit your pre-boil volume you'll leave fewer gravity points behind with the grain.

I've wondered about this on several occasions. Initially I thought speed should not matter but then I started thinking that at slower speeds the grain is in contact with rollers for longer period of time which should yield a better crush. I think of it like a car compactor, the longer the exposure the more "crush".

I run my BC at factory settings at full speed using my corded drill and get 80-85% efficiency. I think sparging techniques are much more important.

I always read that a slower speed would give better results. So I originally ran my mill slow as possible. It really heats up my drill and I don't like that, so I decided to test it out and tried going almost full speed the last five batches. There has been no loss in efficiency or any change that I can tell.

My $0.02 is that your brewing technique could just be improving as you go along.

I have run my drill at full speed (with a JSP MaltMill) and I get exactly the same crush, and efficiency.