I know some of the travel team guys for Losi, they will run stock foams, And/or bomb1 etc... a little stiffer foam, depends on how they set their cars/trucks up, I know they mount up a pair or two a day it seems
I will run mine for a month or so club racing, and mount new ones for qualifying and the main. I don't take the chance of the foam breaking down in the middle of a main.
I'm guessing if you're going to practice thurs, fri with the same tires, then new ones for the sat and sun. just my .02
also a thought, in stock they seem to last longer, if you got a 3.5 in the buggy and the back tires look like pancakes full throttle around the track, ya might want to bring a few extra foams..hahahah