I’m only just starting with Agenda, but I’m finding the styling / markdown shortcuts really fiddly. I can see them really slowing down my typing and thinking.
The best approach that I’ve found elsewhere is in Quip - I like the simplicity of the pop up menu when text is selected, especially the pull down menu for paragraph format, but what I absolutely love is using backtick to toggle through ALL available styles - starting with H1.
I use this all the time - I start writing, without worrying what style/level the sentence would be until the end, then I realise it’s actually a new heading or whatever, and just hit ` (backtick), without any modifier key, to get H2 or checklist or whatever. It’s a real time saver. See here.
(Incidentally, I use Quip for team collaboration and some personal notes etc, but I can see Agenda replacing it for my non-collaborative writing.)