But what degree of procrastination is too much? How do we know we have become chronic procrastinators?

When you needlessly avoid getting important things done, it's procrastination.
Since you enjoy "the rush hour" kind of activity, I'm tempted to say you aren't procrastinating because you intentionally delay. But still, it's procrastination. Maybe it's just you trying to convince yourself that you enjoy the rush of getting things done at the eleventh hour.
I can't tell if you are a chronic procrastinator, seriously. But anyone who procrastinates often is...

When I noticed I was beginning to be accustomed to doing the job at die minute, I decided to be setting my own deadline maybe two days earlier than the original date of deliver.

So it seems you figured something was wrong and you decided to create a solution to not miss deadlines.

Regarding sleep, yes, it refreshes the brain. But if there isn't a solid plan to execute all you have on your to-do list, overwhelm may set in.

Thanks for sharing your thoughts.