I thought I wanted this feature but my issues have been solved by plugins. One plugin will prevent opening duplicate tabs, and instead just switch to an open tab. One gives a nice most-recent behavior to tab switching hotkeys. One hides the tab headers (What good is looking at a pile of x’s at the top of the screen anyway?). One moves the current document to a different tab group.
The upshot of all this is that “tab” is no longer really a thing. I have the left pane document, the right pane document, and a history of documents accessible by ctrl-tab. It’s much cleaner that way.