Ah, interesting. I think we've arrived at a very similar setup, albeit implemented in different ways. I too use a MacBook and external monitor, and fullscreen my apps, but I just let them take up the whole screen minus the bar at the top, rather than explicitly use the fullscreen new workspace feature. I then swap between apps by binding all my most common apps to F1-F6 using Thor, which I find is easier to navigate than remembering workspace positions.

How do you handle split screen? Do you never have two programs side-by-side on the same screen? I've tried doing that in the official fullscreen mode but found the whole experience a pain, so I use rectangle to shift windows left and right.

I use full screen apps on my Mac and switch between them using ALT-Tab. But there is a bug whereby you don’t always get the window of the app showing if you ALT-Tab too quickly, even though it is selected. I might try something like your setup, or the one above instead.

I'd definitely recommend giving dedicated hotkeys (one per app) a try - it's very hard to go back to alt-tabbing after being able to switch so effortlessly. As I say, I use Thor, but I'm sure there's a bunch of alternatives out there.

Whenever I want to look at two things at once I display each item on a different screen.

If I really want to do split screen (very rarely), I press control + up and then drag one screen over.