[mdekkers]

Only a fool breaks the two-second rule: https://en.m.wikipedia.org/wiki/Two-second_rule

[lutorm]

That rule explicitly states that it's not for being able to stop, though, it's just to have time to react to the driver ahead stopping. Two seconds isn't nearly enough to stop in front of a stationary object. At highway speeds it's even barely enough to not rear-end the vehicle ahead if it has to panic stop.

[mdekkers]

Yep, that’s right. Its a great rule though, and as explained in the article it works at any speed, highway or not. Personally I keep 4 seconds.