Accepted and rejected timing pairs share one exact rule. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
The same window accepts one pair
With a 2 second window, a 2 second separation is accepted.
2≤2
One more second rejects the next pair
Changing only channel B by 1 second makes the separation 3 seconds.