One issue with the speed limit argument is this; there's a cascading effect. If you're doing 70mph, 5 or 6 cars behind you may be doing 63mph. Microadjustments, speeding up and slowing down, adjusting following distance, and changing lanes slows everyone down.
A recent study actually found that we could eliminate rush hour traffic more than half the time if we didn't change lanes too much. Many traffic jams, as it turned out, are just caused by the domino effect of people changing lanes constantly. When people are weaving around in traffic, it causes a ripple effect through traffic.
The left lane is for passing other vehicles; the right lane is for driving. While we're at it, make sure you're merging like a 'zipper' onto the highway. You shouldn't be driving alongside cars that are merging. Like a zipper, it should be left-right-left-right. That might mean, while driving in the right lane, you may have to slow down a bit to let a car that's ahead of you merge slowly, or that the car merging needs to slow just a bit to filter in behind you; depending on who is ahead of who. Another great annoyance of mine is people who drone in the right lane with the cruise control on, completely ignoring oncoming traffic. Especially big trucks who are difficult to get around when merging. Sometimes a small adjustment in speed can be the difference between the merging traffic having to dart around, accelerate hard, or brake hard; and both parties being able to make small adjustments to merge safely and simply.
In any kind of traffic or short on ramps; you're 100% right.
I'm not usually in the right lane so I guess there could be a point there about always adjusting speed for mergers or at least expecting to make speed changes based on the entry/exit of other drivers.
But, a couple of years ago I was in the left lane with my cruise set. There was very light traffic but driving in the right lane would have meant switching lanes a couple of times a minute.
Anyway, there was a place where the highway I was on and another highway crossed. The attributes of the area caused the civil engineers to create a left hand merge lane; they did at least make it LONG.
As I said traffic was light. There was 100 yrds or more between cars in the left lane.
A woman merging from the other highway ends up directly to my left with her blinker on. She drives the same speed as me for about half a mile. 30 seconds or so. Then as the merge lane runs out she starts honking and flipping me the bird. She finally hits the gas hard, drives on the shoulder, and pulls in front of me.
The point being; when merging into open
traffic with plenty
of time, it should be treated as any other lane change.
Identify the open spot you want to occupy, indicate your intentions, adjust speed, move smoothly & quickly into position, re-adjust speed to the flow of traffic.