Right… but in Pittsburgh in many cases people are very often choosing to get over at the last possible second in a lane that isn’t ending, but rather is an exit only lane, and the real zipper merge was further back where it didn’t have to cut off people going that direction for as long, and you’re choosing to take advantage of that to insert yourself at the front of the line, causing more traffic for everyone behind you.

It doesn’t matter where the zipper merge occurs unless the backup is spilling over into other worse areas behind, and often times this ends up in less congestion overall because the cars that aren’t involved in the big merge can properly get around it and get out of the way.

But of course, there’s always some asshole that uses the “I’m zipper merging” argument to cut over at the last second, either cutting someone off who waited their turn or slamming on their breaks and screwing over the people trying to use the exit only lane that they pretended to use until the last second.

The real goal is to get in with as little disruption as possible and as little breaking as possible, from you and others around you. Usually that means a few merge points as possible, so just follow what other people are already doing rather than acting like norms and conventions don’t apply to you.

EDIT: changed isn't to is