Ok, well I think I'll stick with the add 1/2 water, drain, add 1/2 sparge water, drain, done method.

BTW I am able to calculate how much boiling water to add to get my 152F mash up to 168F; I just said 2/3 and 1/3 to keep it approximate and easy. (You just use a step mash calculator and knowing my total water used, keep tweaking the numbers until I get the total amount).