I found that when I went with the default numbers for the 10 gallon cooler, my mash temps would be a few degrees too cold. I now preheat with hot water from the tap for about 20 minutes while my mash water is on the burner, dump the pre-heat water, add the grain and mash water and my numbers are right on the money.
The only way you will know for your equipment is to try it and see what the numbers do. You may have to add some boiling water or a SMALL amount of cooler water to adjust the temps. I will tell you this though, raising the mash temp takes a whole LOT of hot water. Lowering the mash temp only takes a little bit of room temp water.
I could play around with the default numbers in BS for my cooler's correct coefficient, but the system I describe above works for me.