I have a column of 4 dispensers, all facing the same direction (to the right). For demonstration purposes, each is loaded with a different color of shulker box.
In the above screenshot, the dispensers are situated next to a 1-tick pulse generator, but not connected to it. By placing redstone dust on either the diamond block or the gold block, the dispensers are connected to the circuit so that the button causes them to activate.
If redstone dust is placed on the diamond block, all 4 dispensers activate.
If redstone is instead placed on the gold block, only the top 3 dispensers activate.
Since the redstone dust is not powering the dispensers, I'm guessing this is some kind of block update issue, but I don't understand exactly how it's working. What explains this behavior and how can I predict how the dispensers will behave inside of more complex circuits?
I'm using 1.13.1 Java edition.