There are so many small tasks that I could, but until now almost never would automate (whether it's not worth the time [1] or I just couldn't bring myself to do it as I don't really enjoy doing it). A one-off bitmask parser at work here, a proof of concept webapp at home there – it's literally opened up a new world of quality-of-life improvements, in a purely quantitative sense.
It extends beyond UI and web development too: Very often I find myself thinking that there must be a smarter way to use CLI tools like jq, zsh etc., but considering how rarely I use them and that I do already know an ineffective way of getting what I need, up until now I couldn't justify spending the hours of going through documentation on the moderately high chance of finding a few useful nuggets letting me shave off a minute here and there every month.
The same applies to SQL: After plateauing for several years (I get by just fine for my relatively narrow debugging and occasional data migration needs), LLMs have been much better at exposing me to new and useful patterns than dry and extensive documentation. (There are technical documents I really do enjoy reading, but SQL dialect specifications, often without any practical motivation as to when to use a given construct, are really not it.)
LLMs have generally been great at that, but being able to immediately run what they suggest in-browser is where Claude currently has the edge for me. (ChatGPT Plus can apparently evaluate Python, but that's server-side only and accordingly doesn't really allow interactive use cases.)