Scheduling: The difference between West Marches and an Open Table

Let me preface by saying I've never run a West Marches campaign in the true sense. If you don't know what that is, check out Matt Colville's video here.

But I love the ideas it aims for. Namely, that 

1. The cast of PCs can regularly rotate 
2. The adventures are largely driven by the PCs' interests

I love the clarification added at the end of this recent video where he says

"We're not going to play again until y'all tell me what you want to do, who's around, and when you want to play." - Matt Colville

This is a fantastic way to make sure that you're only running games for individuals who are motivated to go on the adventure.

The Problem

However, I firmly believe one of the biggest indicators if an RPG group will be successful is a regularly scheduled time. No excuses. No confusion. No problems. We play at the same time every 2 weeks so we can all schedule around it and if an unavoidable conflict occurs, so be it. There are things more important than D&D.

Maybe I'm afraid my game isn't that fun and my players won't take the lead in proactively scheduling. Maybe I should pitch my next campaign to a large enough pool of players that only the most motivated emerge. Mostly, I want to be able to plan my own life around D&D and that doesn't work with a full-time job, a wife, and my first child on the way. I have to imagine the proportion of DMs who can prep and play on demand is fairly small, right?

So what do I do? Maybe it's not so much a West Marches campaign I want to run as merely an Open Table?

But with an Open Table, I think the adventure is largely chosen - probably a hex crawl or megadungeon - to avoid problems of plot continuity, though West Marches faces similar problems unless adventuring groups commit to multiple sessions. Is there nuance in the PCs coordinating what they want to do and with who that can be ported from West Marches to an Open Table? I think so. How do I make that work with regular scheduling?

My (Hypothetical) Solution

1. Pitch the campaign (including rules and setting) to a large pool of players
2. Run self-contained sessions (start and end in town?) at regularly scheduled times
3. Anyone can show up to any session and the players present will decide what to do in that session
4. Encourage players to self-organize between sessions and decide who is going to show up and what they want to explore ahead of time

Step 3 is basically an Open Table. Step 4 is the West Marches. I wonder if I eliminate Step 3, but limit Step 4 to the regularly scheduled time? Here's my revision to the quote:

"We're not going to play again until y'all tell me what you want to do, who's around, and which Wednesday at 7PM you want to play." - Gelatinous Rube