My group plans for every Saturday (on Roll20), coordinating via Discord. We currently have 2 active D&D campaigns, 2 inactive (incomplete) D&D campaigns, plus a game of Scum & Villainy. We generally try to alternate the 2 active D&D campaigns, with S&V whenever a DM can't run or we're short players. Additionally, we had a DM that ran periodic One Shots and I'm working on a mini-campaign.
Group text. One groups tries to gather physically once per month, the other tries to play weekly (usually Wednesdays) via VTT. For both, we coordinate via group text to confirm attendance and/or days/times.
More about set scheduling, and why it's so important. If "Wednesday night is D&D night", then the players are aware of this and don't schedule other things on Wednesday. If it's flexible, it's a crapshoot if everyone will have left a "hole" in their scheduling that works for everyone.
We tried having a flexible schedule for a campaign and it was a mess. Never again.
We all share an online calendar that stretches out over two or three months into the future. Everyone marks the evenings that they are able to play D&D, and whenever there is an evening with enough players, we play.
I'm weird. I run 4 Tuesdays every month (if we have a 5th Tuesday in a month we sometimes just take it off and sometimes we play board games) I then play every Saturday we do 2 Saturdays of one game then 2 of the other... and we have a once a month Thursday night game.
We run two campaigns and each has a tentative set schedule. One campaign is weekly, on Wednesday evenings from 6:30 PM until around 9:00 PM. The other is every other Saturday, from noon until around 5:00 PM. Each has its automatic "next session" figured out ahead of time, which we cancel and bump to the next week depending on if scheduling conflicts come up. But since all of our players and the two respective DMs come from a total of two families, any conflict for one player will almost automatically drag one or more players along so we tend not to play unless everyone can attend. If that means several skipped weeks at a time, so be it.
We have a standing schedule of every other Saturday, 5:30 to 10pm. That schedule only changes if 2 or more of us can't make it (there are 4 of us), or if it is a holiday weekend (Christmas eve, etc.). Out of 26 bi-weekly possibilities, we probably meet 23-24 times a year.
Our default schedule is every other Saturday evening. However, at the end of each session we review the calendar. If anybody can't make it to the next session, we discuss alternatives (move it to Friday? a different weekend? what if we do it at a different location?) to see if there's a way to make it work for everyone. If there is, we go with that; if there isn't, we stick with the regular schedule and whoever can't make it, can't make it.
Around the Christmas holidays, everyone's schedule goes crazy and we just jam in games wherever they fit.
I go by a set schedule - for the one group, we game on the first and third Saturday of the month, and the other (which has shorter sessions), every Thursday. As long as there's at least three people that show, we game.
Back in the 4e days, I used to only run when everyone could make it. We were gaming only once a month back then, and there would be months where we just couldn't agree on a time, which lead to missing whole swathes of months. I eventually gave up on that approach. I've learned that missing sessions leads to more missed sessions.
Two of my groups play a set schedule (every other Wednesday).
One each get scheduled month by month, after the game ends or "whenever player a has a day off that matches all the other folks schedule by chance".
My now-8yo and I have been playing at our FLGS almost every Sunday for about three years now. About six months ago we added another player. As of a couple of months ago we have two more players - 8yo's school friend and said friend 's dad.
Sunday when the store opens has been our time for all of it. That way people can make plans and know we'll in advance whether they can make it or not. And given that not everyone can make it all the time, we now have about three different games going, depending on who's going to be there.
Set schedule for most games, though I'm in a Pathfinder game that meets whenever the stars align - that one's a special case since I joined that group 20 years ago when they had already been gaming together for more than 10 years... it's not really about gaming for them.
I should note my weeknight games (ie every Monday at 7) are very consistent but online, so it's easier to get there so to speak. We still have to cancel form time to time but generally for holidays. My weekend games is nominally every other Sunday but there's fewer players so it's more likely to cancel.
I was normally a big fan of a having a set weekly date for D&D as that allows everyone to keep that time clear in their schedule, but I've had to switch to renegotiating a new date every week because my players couldn't know what day would suit them with ever-increasing workload from the university. I've had campaigns take a 2-month hiatus due to scheduling issues before, but they tend to bounce back if everyone has faith in the campaign.
Our last campaign was every odd (1st, 3rd, and sometimes 5th) Tuesday of the month (as the DM, me, had another standing commitment on the 2nd Tuesday of each month).
Our current campaign, being West Marches (ish), is currently being scheduled when a DM has availability. Recently that has meant the DM offering up two possible weeknights to choose from each week - with the more popular (as determined by player clicked emojis on Discord) night being the one that we end up playing.
Every Sunday at 2 PM - 6 PM. We start on time and we end on time. I have players driving from a fair distance - I want to make sure they get four hours of solid gaming. I have nine players - I usually have 5-7 at the table in any given week. While nine is more than I like to run, it happens very occasionally and it is worth it because I almost never have to cancel a game.
During the fall I have to go bi-weekly due to my job. I am always anxious to go back to the weekly game when December rolls around.