Things it performed badly for me (our of sample):

- Implement quadratic voting (a concept defined in Radical Markets by Weyl). When trying to explain it, it still invented smth that looked good

- Implement a First in first out calculation to file tax returns where within a 1 year holding period, tax rate is 0%. It calculated some really implausible stuff and it seemed easier to just figure it out myself.

- there were many such cases for me, but also good outcomes too