Great article Fei Ren! I am a big fan of JTBD as well.
In your example, you describe “Travel to another city for a conference”as the job-to-be-done. In my opinion, that sounds more like the product or service that the user is hiring to get the job done. The job, I believe, would be to feel more educated in a given subject matter or to meet new people in order to learn more. That being said, traveling to a conference might be competing with an online course or even with a book. And then the struggles of the user totally change.
What do you think?