I depart from that L/R split pretty regularly, especially when coding. I frequently have a single large window taking up half of my screen, and several smaller windows stacked vertically on the other half. The big window is usually the editor, but sometimes the browser if doing web development, or possibly a pdf or something like that. The little windows might be the editor, or a browser, or general command line work, or the stdout of a server or other daemon that I'm working with.

I sometimes do move to more of a tmux split workflow, especially if I'm working on remote machines, but it's just much nicer to have the same keyboard commands for all of my windows.