I didn’t see this as a previous answer and it has worked pretty well for me. I go down in the basement and fill the mashtun with hot water out of the tap and close it up before I start heating the water… by the time I am ready to mash, the cooler is hot enough so don’t have the software adjust for the mashtun. I also have the grain at room temperature and do have beersmith account for that.
I usually put the suggested temp/quantity of water in, mix, wait 5 minutes and may need a small adjustment. After that I wrap the cooler in an old sleeping bag and don’t loose a degree over an hour.
I guess its what works for you… keep track of how you end up adjusting and apply that from the get-go next time. I also like to slightly under-shoot so I can just add a little water to compensate. Overshooting means I have to sit there and stir with the cover off until I get the temp I want… way too much work!