I just had to move a bunch of emails from onprem to exchange online. there's software that already does this well, imapsync, I just needed a wrapper around it to automate it and get nice reports, then I realized there were quirks in how the origin server interacted with it's email clients (not outlook) and how this turns into edge cases and issues while syncing live mailboxes to exchange online (expunge, flags, runs where you get interrupted, cutover times, yadda yadda yadda).

it quickly turned into quite a mess, opus5.5, often on ultra, almost a week of work (that's 7 full days, not a calendar week), I still don't have very precise reports because of all the edge cases (5.5TB of emails across hundreds of mailboxes) and opus5.5 would have basically broken the mailboxes on exchange online at least four times. it's still worth to do it like this, because I keep strict controls over it, instead of buying very expensive email migration software.

same experience with using LLMs (which I do) to write critical code for what are basically CRUDs but actually handle invoicing, warehousing and all those nice critical problems where there's actually money on the line but are not truly deep CS issues.

again, it would have broken things quite a lot if I didn't understand the problems deeply.

then I ask it to implement what is a complex alghorithm for me, while explaining it to me, and I learn new things and improve a lot.

it's still a jagged frontier, I'm not sure how this will go with math