Band-aids are great to stop the bleeding, but not the ultimate answer unless you are fond of buying them. Eventually, you should ask yourself, why do I keep needing to use these crutches? Do I want to keep using them? If your tank is in disrepair, H202, erythromycin, excel overdosing, phosphate limitations all may help remedy the algae short term, but if you don't know why it's happening it will return. I really think that is what people are trying to point out.
My philosophy is this: Use what works for you
. If you like using a particular method to combat algae when it crops up, then use it. Don't worry about what others say, it's your tank and at the end of the day, it's what makes YOU happy that is important. I suspect there are many "algae band-aid appliers" out there that are just too intimidated to acknowledge their dirty little secret.
Has anyone tried a spot dose of erythromycin? It seems a much more controlled method
I would STRONGLY recommend against doing this. Period. The reason being erythromycin is a medication, an antibiotic. If you use it haphazardly, you will end up creating super-strains of BGA and diseases. This should be treated with the utmost respect and not used in similar fashion as excel. Think of how many strands of viruses are now immune to penicillin because of the massive misuse of the drug.