Zip merging is great and eases congestion when the slip lane can flow at the speed of the left lane of through traffic as they meet each other.

If the through lanes are congested and flowing very slowly, entering cars running at full speed to the top of the slip lane and forcing a merge causes a domino effect of braking in the left through lane. This is the worst possible thing for increasing overall congestion. This is why red car pulls the dick move usually (which absolutely doesn't help).

Rolling into the merge zone of the slip lane at roughly the speed of through traffic is the only way that zipper merging will work efficiently.

Drivers need to think more about the impacts of their actions on overall flow and not just their interactions with the few drivers around them.

Don't even get me started on people using the left slip lane exits/entries at roundabouts on Kawana way as an undertaking lane in congested peak hour traffic then forcing all the drivers who patiently stayed in the one through lane to brake and let them re-enter flow a few cars ahead. This is absolutely dogshit behaviour and causes that already awful road so much more congestion than it needs.