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I didn’t say anything about variation between two screws of the same pitch

But this is what everyone else is talking about, because that’s what matters in this case. The manufacturer knows exactly what type of thread they used, and the variances within that type are really small, so they can easily tell how many mm of vertical movement 1/8 of a turn is with high consistency.

If you’re familiar with coffee grinders, they’re basically using thread to adjust distance between 2 burrs. Even there (mid to upper-mid range ones) can’t guarantee the same grind size on the same setting for different unit of the same model

While the coffee grinder example is true, this is not at all due to tolerances in the thread pitch used to adjust the distance.

This is because of the tolerances on the burrs themselves and the sideways alignment varies too much, and why it’s better on more expensive models.

Threads are controlled to a fairly tight ISO standard, which can be done very cheaply because of the simple helix shape and ridiculously large quantities.

Burrs on the other hand are much more complex shapes, in much lower quantities, which is why tight tolerances are expensive on coffee grinder burrs and not on simple thread pitches on standard bolts.

Getting a wire harness so I didn’t have to crimp all the wires myself is the main reason I ordered a kit instead of self-sourcing.