My typical reason is I need to sound less casual than I am in professional emails. Or I’ll ramble. I don’t copy paste but I’ll write an email in my normal tone, let the llm look at it and then fix it up. I’ve also used it to help me find new books when I’m in a draught. List ones I like and it’ll spit out suggestions. Today I couldn’t figure out a website issue so I copied and pasted the html and it generated a snippet of css for me that fixed the problem.