I've never had a pre-glued one last very long. IMHO they're to get you home if you have more than one flat in a day. I'm probably applying them wrong, other people seem to be able to get them to work. But I like glued patches, so I'm sticking with them.

The REAL patches never fail if properly done. In fact if you wanted to try to get the patch off, you'd destroy the tube in the process. The glue should pretty much weld the patch to the tube. The fact that I can peel a glued patch off of the tire at any time makes me nervous of them.

You need to let the glue get pretty dry,but still a bit tacky, before you apply. I also press them together under some weight after that for a half hour or so (I patch when I get home if at all possible).