Yes it does. The only time you will notice the difference is when/if you have to pass through two hexes of rough terrain consecutively. What is so confusing with that statement?
Rather than getting hostile when people can't tell what you're trying to say, how about you rephrase the original statement instead of repeating it. "The only time you notice the terrain thing" is not exactly crystal-clear. Clarifying it by saying "The only time you will notice the difference" doesn't help. Then saying later that you're actually comparing them to knights (and not simply saying that you'll only notice "the terrain thing when...") just makes this even more of a mess.
Through re-reading all of those, I think what you mean is that a knight will move at the same speed or slower than a chariot because if you move one-two hexes with each and the third hex is a rough, they'll have moved the same amount, unless the next tile is also rough. But that's not even true. If they both start on a hex, even if it's not rough, and the next tile is rough, and the one after that is clear again, knight = 2 moves (2, then 1 movement point), horseman = 3 (2, then 1 then 1), chariot = 1. So no, it's
not only noticeable with two consecutive rough tiles. That's even assuming your assertion that you're rarely see two rough tiles in a row is correct, which I doubt anyone here would agree with, and leaving out horsemen.
Also, roads don't make terrain non-rough. Unless you have open borders, you can't use enemy roads, so them roading doesn't have anything to do with this. Unless you're using them defensively, and in most cases, if you're on the defense, you're 1) not moving much anyways and 2) doing it wrong. And in my experience (prince through immortal), by the time forests started getting cleared, chariot archers are nearly useless. And you can't clear a hill. And lot of AI (and players) leave forests in place. And jungles.
God, what a mess.