No you are not. And I found that it is key to pull more and add it until the temp is reached. That is for destination rests where the temp is critical. I don’t worry about this for mash-out decoctions.
There are a number of formulas out there that try to take into account details like mash thickness. But none of them takes into account evaporation during the boil and temp drop of the main mash while you do the decoction. As a result you are very likely to undershoot your target temp. That’s where the frustration with decoction starts. Just take 10-20% more and return the decoction until you hit your target. This process is much easier to control for home brewers. Especially when decoction mashing is a once in a while thing and you haven’t figured out the exact volumes through trial end error.
110 to 133 that is infusion then I pull about 2+ gallons of THICK decoction for every 10lbs of grain.
I’ve never calculated, just pull until it feels right (damn that sounds bad)
I always add top up water that is simmering in a tea pot towards the end of the decoction boil so I always have the volume I started with.
Easy to tell as the pot will have a fairly easy to distinguish line where the volume was at the start.
Yeah, I use the stove too if I need extra burners. Luckily I have gas which I think is easier to use. I try not to have to use it in the winter though to minimize letting cold air in the kitchen and freezing out the rest of the family.