Doing the 4-stroke (per 25 yard length) boomerfly I'm averaging 1:06 per lap (vs 43-53 per lap of easy fly depending on the level of pull/kick force). I do a gentle dolphin of the wall (about 5 kicks) before my first stroke and then concentrate on relaxation, glide and pressing my chest and try keeping it easy. I've done a mile fly twice so far, only because I'm also working on a personal goal of 250 miles this year, and I can rack up my laps more quickly in freestyle than in fly. ;-) I'm tracking my miles on www.buckeyeoutdoors.com
where I use the name butterflyswmr.