chocochipper
I was specifically referring to clean up crews, hermit crabs, emerald crabs, shrimp, snails and brittle stars - not just a single fish. I've read where some people acclimate a fish the way that you described.
When you order a clean up crew from this site, you normally get more than just one specimen. With several bags to contend with, each containing several creatures, if done correctly, and if you follow the directions, it normally takes between 45 to 60 minutes.
Inverts should be acclimated for longer periods in my opinion - especially the snails.
I'm sure it could be done faster, but normally that is how you lose them.
Patience and not cutting corners is a proven way of giving the new animals the very best chance for survival.
Brian