In the vision metaphor, that's called peripheral vision. Some birds, for instance, have eyes on the sides of the head. They're more aware of everything going on all at once. But if you have no sense that time is passing, and the work is interesting, nothing can stop you except physical exhaustion. No sense that the future is getting closer.
Time slips away, imperceptibly.
The hallmark of ADD, the easiest thing to notice, is distractibility. But as Hartmann explained in his book, that's just another name for responding to every signal in the environment. This trait has many implications in the ADD life, but I suspect none are more powerful and pervasive than its effects in time. One is constantly being interrupted, either externally or internally. We learn from what we experience.