I publish four editions of each book, so I cannot upload all four the same day.

I have re-covered more than one series, and again, would only be able to replace three out of four covers each day (so a 20 book series would take almost a month to get all of the covers uploaded.)

Another thing an indie author might do is replace the back matter in several books or a series. Again, I would have to update just three editions per day.

Or an author gets Vellum and decides to reformat their full back catalogue.

There are a number of scenarios in which an author legitimately wants/needs to upload more than three books per day.