I would like to add my perspective on 'Unlimited revisions' after I read all of the comments above.
Im a small seller in vocal recording/singing and i changed my revisions from 2 or 3 to unlimited about a year ago. I did gain orders, not the same second tho, but revisions never went to more than 2 so far anyway. In my perspective im like, if i would be buying, i would be calm that even if the vocals or song will not be what i needed, i have plenty of deliveries available. Higher chance of ordering.
Unlimited works for me, because with vocals are orders so specific, like exact song cover or parody with their lyrics, that they get the same thing over-and-over, with different quality or vocal composition etc. They wouldn't get another song cover, like they would at art pieces as somebody above mentioned.
What do you think about this kind of use for unlimited revisions? I am only sticking to it because i haven't yet have a bad experience with someone abusing this option. Thanks for any answer!