This is my interpretation of deep work too, schedule a time with no distractions and repeat. Over a period of weeks you get better at this uninterrupted concentration. I think Newport's main concern was seeing hordes of students at school sitting in cafes and wasting their time since they were constantly being distracted, and would have been better off going to some library and working in the corner earlier so cafe time would actually be enjoyable or a time to casually talk about assignments instead of spending hours there appearing to study.

For example basic undergrad math proofs I couldn't figure out immediately during 'deep work' I found after a while doing this I could memorize them, so the rest of the day think about the problem in momentary downtime like being on a subway and often figure it out by the end of the day. Before I started Newport's advice I did distracted work and would have to re-read later as I forgot everything.