I have used a LOT of those mini hooks, but not for lights. I'm somewhat embarrassed to admit this, but I have a pretty extensive Hotwheel collection, and I have in the past used the mini hooks to litter entire walls with them. If they can hold a Hotwheel up, they can certainly hold a strand of lights. I've only had maybe two of them fall, but it was undoubtedly because of the surface... not the adhesive's fault. I've never waited to hang anything off them, either.
Some of them do tend to get stubborn on removal, though. I've had the tabs break off so that they have to be scraped off, I've had a few pull chunks of paint, and I've had many of them snap back and wrap my knuckles.