Interesting, can you expand on your workflow a bit more? I'm of the exact opposite opinion - I think Mac's window management is the absolute worst thing about using a Mac - so I'd love to know what I'm doing wrong.
So my external monitor has email, IDE, and misc stuff.
Screen has browser, terminal, chat application.
Pressing control + up allows you to easily reorder and move elements. It's helpful to turn off the default option of automatically sorting your screens
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.
If I really want to do split screen (very rarely), I press control + up and then drag one screen over.