Your comments

I personally believe that the ultimate benefits of "grouped" submissions as a single item go beyond just the submission notification flood issue, even just as mentioned in the initial post. This is ideal for comics, for process pieces, or for multiple connected images in a "batch", like a series of sketches or quick commission pieces done during a stream, rather than loading them separately, or messily piecing them together into one big image.

I would say that a limit on how many images can go into a single submission makes a lot of sense, and it could be a reasonably small amount and still work for a lot of people, but it would certainly make things smoother and easier in a lot of cases.