"They don't use delve anymore" is not really a testament that they became better.

Most of what I can do now with them I could do half a year to a year ago. And all the mistakes and fail loops are still there, across all models.

What changed is the number of magical incantations we throw at these models in the form of "skills" and "plugins" and "tools" hoping that this will solve the issue at hand before the context window overflows.