Our preschooler (3 1/2 years old) demands a band-aid for every minor injury, whether he's actually bleeding or not. I've tried discussing the actual purpose of an adhesive bandage (keeping a wound closed and dirt and germs away while it heals) and pointing out that it will do nothing for a stubbed toe, banged shin, or bumped earlobe. He calmly listens to the explanation, then says, "OK, but I need a band-aid," and points to the bruise again.
Assuming I've got enough on hand that I don't risk running out in case a real cut or scrape needs attention — is there a downside to letting him use them as often as he wants? I'm not sure whether it's fine to indulge in the placebo effect (given his young age, this is unlikely to last), or whether he's learning to think of first aid as a game rather than a serious analytical process.