Chip,
That's not the issue, when it is busy, it can take 20 minutes to get off the circuit after each lap as the queue to get off extends all the way down to the "gantry" , and it is THIS that causes lack of track time . People then get impatient and accidents start to happen. When it was like this in May, I never saw the track closed so often due to accidents - it was almost as bad as this year's ND .