What would you say is the average image size? I have no problem deleting everything above X MBs or above YxZ dimensions.
One problem with judging the pack size is video. Video images add significantly to the size of a pack. And it's hard to judge if they are contributing to the problem or not. So the numbers I will speak of below do not at all account for video images in a pack, which can dramatically increase the pack size.
I convert all my packs to WEBP and shrink their file size before I release packs. So I can speak easily to pack sizes shrunk and not shrunk.
Taking that into account, any pack over 30-40MB is a large pack. Anything over 50-60MB likely has not been compacted. Anything over 100MB has almost certainly not been compacted.