In all seriousness, it depends. If I watch a group, it's so I can see art that I wouldn't be able to find on my own every day. I don't watch it to get a million gazillion ba-whattafuck-gillion amount of pieces in my inbox every day.
A group that has a very large amount of art that could be included (for example, anime, anthro, nude art, etc) should have some sort of standard. While not necessarily a "quality" standard as this is hightly subjective, they could have a set of clearly defined rules as to what is accepted and what is not. On the other hand, groups focusing on a theme or idea that is hard to find probably shouldn't make their standards too high, or there's no new art submitted at all. I don't follow groups so I can see a single update every few months.
Very understandable, Someone else said similar too - popular categories like anime and fan-art, or photography and digital art in general need limits, even if its just submission's per day limits or they'll explode with so much artwork that no-one will bother checking any out. Groups focus on un-popular Mediums and genres can't really be picky since it can be hard enough finding artists for it as is
Must be an active group to post more than one page worth of deviations a day I get around 10 a day tops Usually I comment one sometimes out of obligation though I must admit. Only one in every 100 really impresses me too