I think it depends on the org, I did Product Design at a FAANG and 90% of the design was held back by engineering "appetite" and even then they would implement at best 60% of the UI to spec. This was building semi-niche professional products, not consumer so that was used as an excuse for not wasting time on polish.

That being said, I've recently made a few light weight apps for myself with Claude and I've easily spent 4x the time hand tuning the UI compared to implementing business logic / core features. Super fun tbh