I never change the position of my footbraces. But anytime someone else paddles my boat, the braces need to be repositioned. So adjustable footbraces are preety much a necessity.

It certainly is easier to put them in before the deck is on, but I put my first set in after putting the deck on. I built complete footbrace subassemblies, laid the kayak on one side, and glued the whole subassembly in place.