"One session" is not a very interesting unit of work. What I am interested in is how much less work I am required to do, to get the results I want.

This is not so much about my instructions being followed more closely. It's the LLM being smarter about what's going on and for example saving me time on unnecessary expeditions. This is where models have been most notably been getting better to my experience. Understanding the bigger picture. Applying taste.

It's harder to measure, of course, but, at least for my coding needs, there is still a lot of room here.

If one session costs an additional 20% that's completely fine, if that session gets me 20% closer to a finished product (or: not 20% further away). Even 10% closer would probably still be entirely fine, given how cheap it is.