[tastroder]

That kind of depends on your process. In many cases pdb (or the debugging interface in your IDE of choice) works just fine for that. It's certainly not "terrible".

After the exploration and preprocessing stage I personally don't see much benefit of the notebook model, training/evaluation and any meaningful visualization takes forever anyway, that means I need to cache and persist intermittent results. With that it doesn't really matter all too much if I work on it in vim&pdb, an IDE, or Jupyter.