No I just did a straight measurement, pouring one gallon into the pot and marking the line then pouring the next in. I then filled the pot up with 8 gallons of water and had the Brew Boss system do a 1 hour boil on it.
I set the Brew Boss to power the element at 70% during the boil (easy to set in the Brew Boss program) and I found after a hour that 1.3 gallons had boiled off (update to this I was off it is 1.5). Please note that this is with my atmospheric conditions, you may get a different boil off depending upon your elevation and how humid or dry of an area you live in.
I then drained the pot (with the pickup tube in) and measured the amount of water left in the pot. I found that the pot has 0.25 of a gallon left in it. In addition I ran the water though the ExChillerator counterflow chiller I have and measured the water left in that. (I blew out the ExChillerator with air and collected the water.) I put all of these number into my equipment profile on Beer Smith (A total of 0.5 gallon of water).
Whenever I make recipe now, Beer Smith will tell me I need to put whatever amount of water in my pot, for the sake of an example lets just say it tells me to put 8.5 gallons in the pot. So I put 8.5 gallons in the pot, fill the COFI up with grains, let the system do its entire mash route, and then squeeze the grains in the COFI and let it drip dry while the pot heats to a boil. My efficiency is set for 70% in Beer Smith and I find that I consistently hit the pre and post boil gravity numbers predicted by Beer Smith. When I am done and draining the kettle, I find that as soon as the pickup tube starts to suck air, there is exactly 5.5 gallon of wort in my carboy.
So I basically only measured the water level once at the beginning of the brew cycle, and the system paired with Beer Smith gave me the exact amount of wort I needed without me having to remeasure water levels.