You have some good observations @kewms, but I think OP was only talking about the capture part.
If the goal is to quicky capture a fleeting thought, I also experience too much friction using the New Document Assistant.
@jem Drafts is an option, but you can also just create a shortcut for DTTG that skips all the creation options. As for…
… you can add a shortcut to the home screen 
Or a widget with a selection of shortcuts.
Here is an example shortcut that lets you log something without even opening DTTG, or choose to continue editing in the app:
For the rest, I just use the share sheet extension. If I want to add a quick thought/note I use the comments field.