I’m a bit skeptical, too - but the tester at SectionHiker said they do last (he was using them to treat a bad blister of his own.) However, he didn’t say if his several days were trail days or town days.

I’ll let you know what I find out. (The little devil perched on one shoulder is telling me my instructions to participants should be, “...And the best way to hike is with the laces untied - gives your feet plenty of room to breathe...”