Never. All revision requests are valid, however big. They might not be fair or reasonable but that’s another story.
Dictionary definition: a change or a set of changes that corrects or improves something
Synonyms: alternation, difference, modification, redoing, refashioning, remaking, remodelling, revamping, review, revise, change, reworking, variation.
Seriously, redoing? remaking? Yep.
If you offer revisions to your gigs you’re opening yourself up to the possibility of doing a lot of free work. I’m not saying don’t offer revisions, but do so with your eyes wide open. A buyer can ask for pretty much anything as a revision. I once had a buyer who asked for $20 worth of change on a $5 gig. By the definition of ‘revision’ he was within his rights – according to him.
I’m going to remove all revisions from all my gigs as I rework them and I’m putting my own ‘revision’ definition in the FAQs. I’m still going to fix bugs, and I don’t mind doing small tweaks one little bit, but I’m over doing complete reworks and having to compensate for a buyer’s poor or incomplete requirements or their subjective definition of ‘correct’.
I’ll fix my mistakes for free. I’ll fix their mistakes for a fee.