I remember Jeremy from fast ai was an advocate for notebook centric flows. But I have to respectfully disagree that he is a good authority on maintainable / scalable coding practices like this. And though I may be wrong, I feel like the fast ai lib itself is a not too useful wrapper around pytorch and people would be better served just learning pytorch itself. I say this as someone who watched a year of the fast ai videos, and got really excited about ai because of the fast ai course, which I am still grateful for. But this is my current take.