I disagree with their ideal way of zipper merging. If you move out of the soon-to-end lane early, all the cars behind you will zoom past. The slow-down will happen regardless, but it will be slower in the merged-into lane because it's already full of early mergers in it.

Every once in a while, I've noticed a big truck move over to block the zoom-by merge lane, and if he's ahead of me, I save his space. It really does work better as a zipper and not a main-lane and a bypss-lane.

I've also let two people in in front of me when I notice the guy behind me has cut off the car that should have zipped in.

DC Beltway drives are experts in zipper merging, IMO. Not to mention skilled (most of the time) bumper riding.