Different models have different (daily/weekly) limits and are better at different things.

o3 was for a self-contained problem I wanted to have chewed on for 15 minutes and then spit out a plausible solution (small weekly limit I think?)

o4-mini for general coding (daily limits)

o4-mini-high for coding when o4-mini isn't doing the job (weekly limits)

4o for pooping on (unlimited, but IMO only marginally useful)