I am always in awe of people like you. I have no idea how someone can type \frac{}{} faster than I can draw a horizontal line (while listening to a lecturer), but I believe you.
Meanwhile I use Onenote. I don't have to worry about keeping notes safe, or the stress of trying to type at warpspeed. I would go with a Remarkable tablet but now with subscription pricing it's a non starter.
Latex specific ide \frac and auto fill.
You can for sure get speedy with practice!
Those beautiful graphs now… I ended up using secondary programs to gen images (pdf or whatever) of graphs and such for latex to bring in the usual way. Not as good!
My recollection is that the main speed advantage lay in being able to copy-paste the previous line when working through a derivation.
I live-LaTeXed notes for a couple of years in undergrad but eventually went back to pen + paper (approximately all my assignments continued to be typeset, though).
Meanwhile I use Onenote. I don't have to worry about keeping notes safe, or the stress of trying to type at warpspeed. I would go with a Remarkable tablet but now with subscription pricing it's a non starter.