That's a weird bit of reckoning at the end. If you're short an hour of work, an hour of work is all you need to catch up.
If you could somehow save your brain state in an instant, teleport directly to the meeting for an hour, teleport back, and then reload your previous brain state as you returned to your work, it would take exactly an hour to catch up.
The fact is, it takes a bit of time to change gears for the meeting and then quite a bit more time to get back in the creative zone. Aside from just remembering all the details of what you were working on, it takes quite a bit of time for your body, including your brain, to get into a state of "flow".