I do a single batch sparge with BIAB with 2-2.5 gallons of 168* water in a spare ale pail. Lift the bag out of the kettle after 10 minute mash out, drain a bit, tie off top with a rubber band, lift into ale pail of sparge water, cover, insulate with ski jacket, leave for 10 minutes. After 10 minutes, lift back onto the kettle onto a canning rack, squeeze the H out of the bag, dump the grains right into the garbage (live in the city in a rowhouse and don't have space to compost). Add sparge water to boil kettle. Rinse the bag while I'm rinsing out the ale pail. Boil.
Last brew came out at 78% mash efficiency, though I have gotten as high as 83%. A full brewday from pulling equipment out to cleaned up and me on the couch has taken as little as 3:45 with a 60-minute boil, 75-minute mash. Well-under 5 hrs. though for a 90min boil.
The only thing I haven't done is make real big beers this way, most have been under 1.070 OG, and I've heard you can lose a lot of efficiency on big mashes. I suppose you can always supplement with extract.
Just putting this out there in case people are nervous about making the jump to AG. BIAB requires a bit of heavy lifting (literally), but almost no additional equipment, and is also great if people want to minimize gear. I will say I do have a 40q kettle, a homemade copper IC, and a blichmann floor burner, which can get me to strike temp in under 10 minutes, and from mash temp to boiling for 7.5-8gallons in about 20. Further, I've done as many as 7 brews on one propane tank. My God I love that thing...1-year anniversary present...Psyched to brew this weekend!
On Tap: Brett Saison, Bo Pils, Weizenbock
Cellaring: Lacto Calrysian, Cider; Freezer Cleaner IPA
Planned: Fo' Pils