I could see that for a few reasons. Someone new to Amazon adding their entire library at once, an updated edition of a long running series, different language versions of the same book, etc. Probably not many (any?) legitimate authors writing 3 books a day, but there are lots of instances where an author might be trying to add several at once.
Something like 60/month seems like it'd be a little more reasonable to allow these legitimate upload waves though.
> Something like 60/month seems like it'd be a little more reasonable
That would cause scammers to create new accounts, upload 60 books, hope to sell a few on the first few days until they get caught, then rinse and repeat.
Amazon will probably also monitor accounts who upload 3 books a day using some heuristic so that they can stop it before it becomes an issue.
Something like 60/month seems like it'd be a little more reasonable to allow these legitimate upload waves though.