Great question Kayse,
And the answer is yes. You will need to fur out all the studs on wall that butt up to pan
This is why it is best to have all the drywall removed entirely around the shower area. Otherwise you would have a 1/4″,or what ever sized furring strip size, unevenness from drywall to kerdi board
I personally like buying a piece of plywood and rip down 2″ strips to nail or screw over studs. Its usually the cheapest way to go
