That's because Russia took fuck all in 2023 when they were stuck at Avdiivka for months and months, way longer than expected by all sides. Once it fell, there were fewer natural choke points for Ukraine until Pokrovsk, and defense lines were not well prepared enough. So comparing taking a lot of fields to sending troops to capture a static point for a year is not really apples to apples imo.

Kursk is and always was a gambit. My view is that losses and disorganization on the frontline from Ukrainian's part on the Donetsk side, is independent from the results of the Kursk incursion, not because of it. As such, whether it was a overall good idea or not in hindsight, it appears that the primary objective of the incursion was met, as every troop, NK or Russian, stationed to recapture Kursk is one fewer re-inforcing the offensive in other areas.