I don't get lower efficiency with wheat. This could be because I might crush a bit finer than others. It could also be because I only use Great Western white wheat which has a grain size comparable to 2row.
I'm not sure how I do it, but I nail my Beersmith predicted OG 90% of the time. Crush grains myself. Never adjusted the gap. Mash pH of 5.2-5.6. Single batch sparge. Semi-accurate +/- 2* mash temps in a cooler. 45-60 minute mash.