I have been using key shortcut chaining in my WMs for freeing up more application hotkeys and also make them easier to remember. And it it still quite fast.

Starts them off by Ctrl+T, then for example: A (Audio) - [P, Pause; N; Next; V, Volume] R (Run) - [B, Browser; I, Inkscape; S, Spotify; Q, SQL editor]

And a lot more. The mnemonics helps me remember them, and Ctrl+T, R, B is quick enough to launch a browser.