We want the throughput of the road to be as high as possible. Broadly, that means maintaining the optimal (minimum) spacing to make the merge safely without changing speed, while maximizing speed.

You may get larger areas where speeds are disrupted, but on the average be going faster. Stop-and-go traffic introduces tons of inefficiencies since drivers need to be much more cautious than in a consistent traffic flow.

The big challenge is that it’s basically impossible to know what the optimal speed is, since it relies on knowing the detailed state of the road and traffic volume miles ahead of what you can see.

Self-driving cars are interesting here since they will open up new opportunities for all the vehicles on the road to co-regulate their speed near to the optimum.

What I tend to see instead is hard braking ripple back down the line to a half-dozen cars or more for each car trying to merge right at the end because suddenly there are two cars right next to each other and one lane of car width left. Every time it appears that the lane-ending driver is like "oh wow, my lane went away!"

The goal is to have both lanes move slowly, but constantly. To basically have a "1 and 1" progression through the chokepoint: 1 from the left, 1 from the right.

It is a rough balance because you have those who don't want to let others merge at all. And there are those who want to merge at all costs. Both of which violate the "1 and 1" guideline which gives everyone at least the illusion of progress.