I configure my Emacs to avoid splitting the frame into multiple windows -- similar to how a web browser never splits the browser window into multiple viewports. (Also my Emacs never makes a second frame.)
(The way I achieve that has changed over the years because the old way stops working.)
The way I do it now, the frame does split in some situations (e.g., when Emacs shows me a *Completions* buffer) but AFAICR I never need to manually invoke the delete-window command to get rid of the second window: it always goes away by itself.
> I configure my Emacs to avoid splitting the frame into multiple windows
Is that to address a particular problem?
I use multi-window frames a fair amount. (Latest Mac OS, latest Emacs.) I've noticed that sometimes a multi-window frame will seemingly freeze up and be unresponsive to the keyboard or trackpad, including multiple Ctrl-G commands. But then C-x 5 2 will work to create a new frame. And I can go back to the frozen frame and C-x 5 0 to kill that frame.
For me, it doesn't make sense to have my application's functionality overlap with my window manager. Having two separate methodologies and sets of keysbindings to move and switch between areas of the screen depending on what happens to be in those areas is arbitrary and inconsistent. The way I switch between Firefox and LibreOffice should be the same as the way I switch between two text editing windows/frames. I therefore prefer to use frames rather than windows in Emacs, and let my WM handle them. For the same reason I've never seen the appeal of tmux pane management. If I used a WM, Emacs windows management, and tmux panes, I'd need three different ways to manage what are essentially all the same concept.
For example right now I have Gnome configured to scale the UI by a factor of 200%, which means that my display will fit only a quarter as many UI elements (e.g., letters of the alphabet, icons) as it would if I ran at a scaling factor of 100%.
(I'm not using a HiDPI monitor, just a 1080p one.)
(The way I achieve that has changed over the years because the old way stops working.)
The way I do it now, the frame does split in some situations (e.g., when Emacs shows me a *Completions* buffer) but AFAICR I never need to manually invoke the delete-window command to get rid of the second window: it always goes away by itself.