I heat my strike water in my 30qt pot. I used to take out some for my strike water then add more and heat to mash out temp and use an igloo 5gal as a hot liquor tank for fly sparging into my 5gal tun. The Igloo holds temps wonderfully. That way the water is sittiing waiting for use at temp.
I've lately started boiling the whole pot and mixing the water in the mash tun down to my strike temperature (there are calculators for it). Then I add the remaining water to the hot liquor tank to mix my mashout/fly sparge at 170deg and the HLT holds at a ready.
All my water gets heated to a boil at one time and I dont have to watch a pot to hit a temp. If you know the temp of your tap water you can calculate how much to mix with boiling for a certain volume/temperature.
Results, water standing ready and one free brew pot. Now go find something else to spend that brew pot money on.