Discretion. If it’s congested or gridlocked, it makes no sense to dart and speed from lane to lane. It’s physically impossible.
Now if the roads are clear, there’s some wiggle room. Going 80 in a 65 ain’t that bad. 5-15 mph over the limit is not that endangering if you’ve got a good gauge on the traffic.
Now if you’re going like 110, 120, 130+ mph you’re just being an idiot and jeopardize everyone.
If there isn’t much traffic, specially on certain days and during certain hours when you know there isn’t much traffic, you can go certain speeds without jeopardizing everyone else.
Reckless drivers are a special breed of stupid though. Like people who speed in plazas and areas with heavy pedestrians