It is more work, at least at a class of restaurants good enough that you're trying to synchronize everyone getting their entree at the same time.

Larger parties also tend to occupy a table longer, and in some groups, tend to tip less -- because people underestimate their share of tax and tip, or potentially maybe sticker shock if one person is hosting.

(The former is from direct experience, not as a server, but trying to generate spend on cards: with larger groups of coworkers, I found that if I pass around the bill to have everyone figure out their share, it was rare to get shorted on the original bill, but nearly 100% that we'd end up short on the tip -- whether precalculated by the restaurant or not. Makes it not worth it, unless you've got friends who order in a close enough range of items to do the "OK, everyone pay $xx. )