You've hit one of the core problems, but your perception of what Cal recommends and what you should do to achieve deep work is wrong.
For deep work, you should be able to block a chunk of your day to do important tasks without being interrupted. That's not the same as organizing the day by hours. This blocked chunk can be dynamic to accommodate emergencies, but you must be able to say nobody should interrupt me for the next few hours at some point in your day.
Otherwise how can you engage in something deep? I've been in this situation many times. I can't do any productive work in my office because there's an endless stream of interruptions, emergencies and stupid things going on. That's why I have to resort to doing all significant work at home, where nobody can annoy me.
I was not in position to block away time like that for years. Currently I am in such position, but that is rather exceptional state. (Home was worst than in work actually.)
For deep work, you should be able to block a chunk of your day to do important tasks without being interrupted. That's not the same as organizing the day by hours. This blocked chunk can be dynamic to accommodate emergencies, but you must be able to say nobody should interrupt me for the next few hours at some point in your day.
Otherwise how can you engage in something deep? I've been in this situation many times. I can't do any productive work in my office because there's an endless stream of interruptions, emergencies and stupid things going on. That's why I have to resort to doing all significant work at home, where nobody can annoy me.