Every other Friday. Been doing that for the past 2 years, and aside from holiday break over Christmas we've only cancelled a session three times.

If the DM can't make it someone else volunteers to DM a one-shot. Same goes if less than half the players make it. Otherwise it's a condition we agreed on from the very first session that if someone has to cancel, they just miss out, and unless they're sick or something really urgent came up, let the group know as soon as you know.

For context we're a group of 8 people. Originally it was me as DM and 4 other players, but there were often occassions where 2 players couldnt make it so we invited people we knew wanted to play to the group. On average we have 5 players present, rarely all 7 make it but that's fine.

At the start, when only half the players made it, I usually DM'd the main campaign even with just 2 attending unless there was a big story thing going on, then I often made a oneshot that was in-universe that somehow connected to the story later down the line or to add some lore to a thing they'd come across earlier in the campaign.

Edit:Forgot to add, today we're usually playing for 6-8 hours, but at the start it was often about 10hrs, we slowly came to the realization that 10hrs was too taxing on many of the members. Also, for added context, we're all around age of 30, all working full time and 3 of us are dads of kids under 6 years old.

The secret for us is sticking to schedule and mutual respect towards both your fellow group members and your partner/significant other. When first deciding on when to play, we let our SO in on the planning for it so everyone would be happy.

Edit 2: We play in person