Fun, fun, fun, kids, but no one has addressed how this problem arises in the first place and there are three causes typically; cheap metal screws, inferior Allens (hex wrenches) and dirt and grit in hex head. Cheap screws strip easily when the wrench doesn't get a decent fit in the hex head and inferior wrenches do the same in good hex heads. To save all the other hassles make sure you clean out the hex head to be unscrewed before you do and the problem will almost completely disappear.