When I was college-aged, several of my friends would meet at the same pool hall every Saturday night. We'd play pool or sometimes darts and shoot the shit. Usually was only 4-6 people though, but sometimes it'd get up to 10. It never got boring as the pool always kept it interesting, you could always try to get better, and change it up between a few different types of pool (Cut Throat, 8-ball, and 9-ball, mostly).
There was another time when there was a weekly karaoke group I hung out with. Again pretty small, like 4-6 people usually. Always the same place. Seeing who would go up to sing (from other groups besides our own, too) and what songs they'd try kept it interesting.
There's also a Friday night board game group that I've now been a part of for about eight years now, that's had it almost every week. I haven't always been able to go, but I've probably been to probably at least two hundred of them at this point. It used to be more open and would have 6-12 people there regularly, but the guy who hosted it (out of his house) originally got tired of doing it, and when it migrated to another host it whittled down to only 5 core people. But even at the new host's home that's been going for like four years now (without me and another guy for most of 2020-2021 because of the pandemic).
So yeah, having some sort of game or activity it centers around tends to help, at least in my case. Especially something that doesn't require specific people and if people can drop in or out pretty easily (people can arrive late or leave early and no big deal, they can still jump into a game or sign up to sing a song, etc).
Dinners don't work quite as well, imo, because it requires people to arrive pretty much at the same time.