I don't see how it's possible to mashout properly with batch sparging in a cooler as many are doing. It's too much mass to heat up with just boiling water. You would have to fill the entire cooler with boiling water to get 3+gallons plus 10+lbs of grain plus cooler up to ~168*. This would leave you with no water to sparge with and/or require an extra long boil.
For batch sparging with a cooler, Yooper's method of doing the first sparge with extra hot water after draining first running seems much more practical and would achieve similar results. With this method, those first 3+gallons are drained so you only have to raise the temp of the grains and the cooler to ~168* which can be done with a reasonable amount of water.
I tried this method last week with a batch of pumpkin porter and even with 1st sparge at 190* water, I was only able get it up from 152* to just over 160*. I have to admit, this scared me a bit with worries of tannin extraction but Yooper said it works so it must be true. Krausen is just starting to settle down so we'll see how it turns out.
If you have a direct fired MLT, a traditional mash out is much more feasible. Just turn up the heat.