http://trafficwaves.org/seatraf.html

There are 2 aspects to "zipper merge" and people often accept them together when really they should be separated.

Zipper merge advocates usually prefer a style of merging that does 2 distinct things: (1) alternating traffic between the two merging lanes, and (2) using the lane all the way to the merge point even if you have to slow down to do it.

But as the animation on the above page shows, it is possible to do (1) without (2).

Yes, when there is a merge we should try to alternate which vehicle gets to proceed. But we shouldn't go all the way to the end, but rather, we should go near the end, but merge into the continuing lane at speed, so as to maintain the speed of traffic on the road.