I have a simple 2-vessel (mash tun + kettle) HERMS, I prefer to no-sparge or minimize sparge volume as its just another step (I collect water from my kettle/heating vessel when draining and then pour it in the mash after the wort's pumped out). Anyhow - I spent a while digesting BrauKeiser's batch-sparge model/analysis and come up with this SUPER simple rule of thumb that achieves all my main goals while being easy to remember and implement:
"Mash with your boil volume, batch sparge with as much water as your grain absorbs" or MBSA "Mash Boil, Sparge Absorption"
There's a few interesting caveats here:
1. this works to produce worts up to 1.1 OG, after that the mash will get thicker than 1.2 qt./lb.
2. if you're sizing this process to your mash tun (to understand your maximum) you'll find that the amount of sparge water may require more than 1 batch - this is actually very elegant as it will require a # of batch sparges that keep efficiency close to 75% without you have to do complicated calculations to hit a consistent efficiency.
I know there's a lot of assumptions here and that efficiency tends to drop as the beer gets bigger, but each time I do the math for different scenarios its surprising how close it works out. Plug it into BrauKeisers analysis/formulas... it's amazing how well it works out!