Article: Defensive Driving Rule #32: Be A Safe Passer
There appears to a mistake here regarding passing: The least amount of time spent in the oncoming lane is the safest.
In some states, such as Washington, not only is it legal, but the state-published driver's guide tells you to exceed the speed limit long enough to safely complete a passing maneuver. "Why?" You ask. It is simply to reduce the likelihood of taking up too much roadway and putting yourself in danger of a head-on collision.
How many times have you seen it when in a 55mph zone, someone is doing around 40, but when you begin to pass them they step on the throttle? I have seen it many times. Hence the need to make proper use of your own throttle to avoid an unpleasant experience.
Even so, if those ahead of you are going fast enough, then why bother passing? You won't gain anything that's worth taking the risk. Thank you.