My circle of friends shrunk some during the pandemic and after the vaccines came out I put a lot of effort into building it up (larger than before). Some data in case helpful:
Friends made over 1 year, 3 months:
Meetup - 1 friend. Had a poor time-to-friend ratio for what I put in, but that's an n=1 and I mostly frequented just one meetup, although I tried like 3. Negative experience overall (for me, ymmv). Friend is great.
Local discord group around a hobby of interest - 2 friends. Many friendly acquaintances. Had to find the right group as a few I tried didn't feel like as-good fits. Positive experience, the friend making process was enjoyable and the friends are great.
Meeting at an intro class for another hobby (a semi social one - need at least one partner) - 2 friends. We were all new at the intro class and it was hard to find people, so we swapped numbers. Got to know each other through the hobby then became friends. Probably would be difficult to replicate intentionally.
Friends of Friends - 1 large group. 5 that I'd call friends and several more that I'd call group-friends or friendly acquaintances.
Friends of Friends are exponential. There's an excellent time to friend ratio, and the people you meet come pre-vetted. But note that some friends may be hesitant to make inter-friend connections even after they know you well, depending on how closed-off their other groups are. It's, of course, also not generally accessible until you have enough of a circle that like/trust you enough that you're getting invites to their other group things.
Friends made over 1 year, 3 months:
Meetup - 1 friend. Had a poor time-to-friend ratio for what I put in, but that's an n=1 and I mostly frequented just one meetup, although I tried like 3. Negative experience overall (for me, ymmv). Friend is great.
Local discord group around a hobby of interest - 2 friends. Many friendly acquaintances. Had to find the right group as a few I tried didn't feel like as-good fits. Positive experience, the friend making process was enjoyable and the friends are great.
Meeting at an intro class for another hobby (a semi social one - need at least one partner) - 2 friends. We were all new at the intro class and it was hard to find people, so we swapped numbers. Got to know each other through the hobby then became friends. Probably would be difficult to replicate intentionally.
Friends of Friends - 1 large group. 5 that I'd call friends and several more that I'd call group-friends or friendly acquaintances.
Friends of Friends are exponential. There's an excellent time to friend ratio, and the people you meet come pre-vetted. But note that some friends may be hesitant to make inter-friend connections even after they know you well, depending on how closed-off their other groups are. It's, of course, also not generally accessible until you have enough of a circle that like/trust you enough that you're getting invites to their other group things.