You should realy leave the valve alone once installed, it's easy to forget to screw it back in when your froth'n to get out there. Plus some manufactures suggest it can shortern the life of the rubber ring that makes the seal on the screw part. But if you've dinged your board and there's water in it, some people do unscrew it to release the vacum / presure to help get the water out before the ding fix
