Whenever I have to patch a hole I automatically double-patch it. I use Boxers right from the start and prefer to patch with scraps of liner as they are thicker than the clear patches, and seem to hold more permanently. So a 1/2" hole will have a about a 3x3" patch first, then a 5x5 or 6x6" patch over it. I work especially hard to ensure the edges are sealed and use a black rubber tile roller to ensure the glue is everywhere. Underwater patching is a pain but with practice you get better. You have to watch the glue doesn't float onto your skin and hair, and wear goggles for safety. You do NOT want that stuff floating into your eyes! Use old goggles that you can throw away if you must if the glue gets on them, or can save for the next patch.