[throwaway8689]

Implicitly, on-demand is also rapid. I can look up how to use a library in minutes and hours. Most people don't have jobs where they can allocate weeks or months to learning theory that they didn't need before. But such situations do exist: employers send staff on courses, and people sign up for part time degrees.

[joshpicky]

As I see it learning “on-demand” is good enough for most programming tasks. But I agree with the blog post tat the situations you mentioned where a person can actually learn new theory and perhaps push the boundaries are increasingly rarer.