the fact that they must merge is really dependent on the distribution of cards within the deck, though. For example, imagine if your deck was filled with 9s. You would get 2 paths merging but not much else.
Of course with the standard 52-pack you'll end up with a high degree of merging. I just think it's important to say that the necessity of merging is really dependent on the instruction set, so to speak.
I think the fact the deck doesn't have many repeats of 9s. It has lots of repeats of 5s which causes merges and the other numbers will eventually merge. You have 4 each of 6,7,8,9. If you repeat 9 4 times there will be no more 9's and it will merge.
Of course with the standard 52-pack you'll end up with a high degree of merging. I just think it's important to say that the necessity of merging is really dependent on the instruction set, so to speak.