It’s rare, but I think they’re referring to when it’s open enough and running at optimal speeds. It happened the other day on a side street during an off hour, the free lane couldn’t cut to the front without going like 70mph in a 40mph zone.
Of course a muscle car did just that, but still.






If it’s a lane closure, yes, you zipper merge at the end-- imo, because you need visual confirmation of what’s happening but also because it’s predictable and usually both lanes are already matching speeds and zipper merging ahead of you. There’s no need to complicate things with an early swap. Granted, I rarely see a lane closure warning more than 100 meters, if at all… in my tiny car, the best indicator that we’re merging is sudden lane changes of everyone in front of me.
Where I draw the line is when there’s an exit only lane on a freeway and people are zooming along and suddenly want in. Did they jump into that lane just to get ahead? Or are they a helpless victim of circumstance from the latest onramp and unable to merge until now? I let them in, but I’m usually bitter about it.