I treat the blocks of time more like versatile soup ingredients than a rigid jigsaw puzzle, so I am happy to move them around as I'm planning the next day.
I like this analogy of the calendar working like a puzzle where I can put and arrange pieces of my time as blocks. The problem is making a daily plan then scheduling my whole day simply doesn't work for me. This system feels too restrictive, and believe me, I tried it. It was creating unwanted stress and admin work because I got into the flow, ignored notifications then rescheduled stuff constantly.
I like the idea though. Also, currently I have a longstanding problem reviewing my right task lists at the right moment. Using my calendar, I'll try to schedule blocks of work categories, like @Home or @Admin which are representing context lists in my GTD system. I hope it will start to form at least a list review habit for me, so I can start to trust more in my system.
The secret for this—as with many things—is trying to not overdo it.