Does that kind of musician also spend time practicing?

Because the comparison we’re being offered is to a concert musician, and their work routine is likely very different to a music producer.

It's all relative of course. But keep on mind that 700 hours is about 4.5 months of full time work. I sure have had epics lasting much longer than that. And the "concert" is just shipping/launching whole I'm already working on the next epic. Maybe later on we bug fix, but we never truly get to "own" a feature the way a musician owns a song and gets to re-perform it in their repertoire.

I'm not really trying to establish which is harder or easier. Just that the pipelines and layoffs differ immensely.

And

In this instance what would qualify as “pursing fundamentals” for a producer as defined by the author?