Technically speaking, speed limits are set for worst conditions.

As in very rainy, very windy, poor visibility, etc.

So no, in your day to day life in ideal conditions — you do not need to follow the speed limit. Am I saying go double the speed limit? No. 10 miles above the speed limit is fine, though.

That being said, people who tailgate others can go fuck themselves. There's never a good reason to be so close behind another car.