I had to do me expenses this morning and one task is to split out the bill into Room, Taxes and Dinning. I asked gpt-4o to handle and it was a few dollars short. I then asked it to check and be careful and it produced A/B alternative response where A was actually correct when it figured out it's calculation was short of the provided total in the bill.
It could not be trusted to get it right first time and hence I had to do the calcs as well as check it's response - so rather than making me more productive it made me worse.
A rule based system might have been better or perhaps loading the data into a DB or data frame and getting it to produce the SQL and run that instead.
Either way this simple task could not be solved by the best LLM model out there.