Excuse the sermon, but whether on a bike, or a car, I notice a majority of people following other vehicles too closely.
Of course, 'tailgating' is stupid, and more so on a bike.
The main reasons I don't tail-gate are:
If my attention drifts, and the car ahead of me does something stupid or stops suddenly....I have more time to react!
You can't always see what's ahead of the vehicle ahead of you, particularily large vehicles. (Van, trucks, RV's) THEY may not be paying attention. If there's some debris int he road they're gonna hit, or try to straddle at the last moment.....you may not have the space and time to avoid it.
Large trucks frequently use recaps, which are prone to volatile self-destruction...which can send heavy chunks of tread flying. The noise alone is enough to make me wet my pants, if I'm close enough.
Give them space....they also have MAJOR blind spots behind, and alongside of them.
The obvious one is directly behind the truck. "If you can't see his mirrors, he can't see you", pretty much holds true.
( The other problem area is alongside the cab of the truck, where you're transitioning from being viewable in the mirrors, to being viewable in the peripheral vision of the driver.)
It's real tempting to creep up on a car when you're looking for an opportunity to pass. Try to avoid it, you lessen your view of what's ahead
and may annoy the driver....inciting some stupid reaction.
You also can't assume the driver will actually use turn signals if you try to pass on a secondary road if they decide to turn.
One more reason not to pass in the Southern US. Some people still chew tobacco!
Likewise, a tossed cigarette can make life interesting when it hits some bare skin....