For me, no sparge efficiency depends on the OG. My "normal" is about 83%. No sparge on a big beer (1.100) I get in the 55-65% range. No sparge on a small beer (1.045ish) is more like 75-80%. But I use different no sparge techniques on each of those. For the big beer, I add no additional water after the mash...simply run it off and that's my boil volume. For a small beer, I mash at maybe 1.75-2 qt./lb. After the mash is complete, I add in the amount of water I need to hit my boil volume and run it all off once once. To me, both of those are ways of doing no sparge.