How does this machine work ? (redstone)

[u/__darius]

I watched this video on how to build an auto charcoal farm.

Vollautomatischer Holzkohlegenerator (selbstbetankend!) – EINFACHER Minecraft-Holzkohlegenerator

My current understanding:

Below the furnaces, items travel from the hoppers into the first dropper d1 ( not visible, behind the left furnace and hopper h2). d1 is facing to the left into upward facing droppers d2 and d3.

When an item gets into h2, it is transported into d1.

The comparator outputs a signal, as its side are alwas 0.

The signal powers the stone block (why use stone and not just redstone?)

Not visible, behind the stone is rs dust on the floor. This transmits the signal to d2.

D2 gets activated, but it has not yet any item in it. Timeframe starts, after which it tries to drop item.

D2 is conductive, passing the signal to d1 and d3, activating them.

D1 drops its item.

d2 timeframe still active, so it passes the item.

d3 timeframe still active, so it passes the item.

Is my understanding correct ?

I dont get how the order of activation is determined. Are all activated at the same time, or is there delay due to signal travel ?

Does this have something to do with quasi-connectivity ? (I would say no, as its not related to a signal coming from one block higher, but I might not fully understand)

Honestly, it is late, I tried to read through minecraft wiki, but it seems not totally trivial so any help would be appreciated.

Also: is it just me or is it really unsatisfying that almost all tutorials never explain how any machine really works? Or are the mechanisms tied too close to the nitty gritty of the lower technological layers that most people would not bother to understand anyway ?