I used to do "schedule sessions when we can" and have moved away from it. Now with a single exception every game I play is "we meet X" - every Wednesday, every other Monday, etc.
One extended group of players and DMs is all about Facebook. We use Facebook chats (one per game), not facebook groups, but I clicked it as the closest. Again, the default is we are playing and you will be there, and it's on everyone at the table to pipe up if you won't be there. And that doesn't cancel the game (except the 4-player subgroup that doesn't like playing with 3 players), it's when a second can't make it. We had someone no show/no call recently and that caused a good amount of drama - we're serious it's your responsibility. And when I say drama, I mean talk about dropping them and replacement players. This system works for several games.
The last game is also the same regular meeting, on the players to say if they won't be there, but uses Discord instead of FB chat.
The one exception is a game I run for my kids, niece and nephew. Between HS schedules and extra-curriculars, college schedules and extra-curriculars, and the fact that it's an in-person game where not everyone can drive/has a car and starts in different places, that's scheduled "whenever". I'm GM for it, and I've told the players that as part of their adult training they are in charge of planning it, not me. It meets a bit less than I would like, but they manage.
EDIT: One additional thing - we have one DM/player who has sworn off FB as a while, but runs FB messenger on their phone because it's a good contact point for so many friends. So the FB Chat vs. FB Groups is actually a rather important distinction.