This is a discussion that comes and goes over time - accompanied by much argument.
There are two schools of thought regarding droop.
First is that it is not, strictly speaking, affected by tire wear because it is the AMOUNT of drop-out from the chassis to some point measured at the end of the suspension arm (AE Gauge method). Tire wear is completely irrelevant here since we're not measuring anything having to do with tires. This is the DIFFERENCE between ride height and the amount of down-travel each arm has - call it down-travel instead of droop (D-T). As the tires wear down (we're talking foams here) this will not change.
The Second IS affected by tire wear because it is measured as an absolute value. It is the measurement, with the tire on the ground, of how far UP the chassis will travel. Use a RH gauge, hold the tire to the ground, and measure with the chassis lifted as far up as it will go - measure at all four corners. This IS affected by tire wear simply because the tires ARE a measure. Call it full-extension-RH (F-E-RH).
so, which is right? Again - different schools of thought.
Personally, I think the second is more important. Essentially, it's the RH at full extension. If, as you wear your tires, both your RH and full-extension-RH decrease, your handling is going to change, then you must make adjustment for it by adjusting BOTH your RH AND your F-E-RH. But you really need a base setup to begin with - that should include a starting tire-size, standard RH and D-T (which will establish a beginning F-E-RH) - then throughout the day you can adjust the F-E-RH and RH as needed.
I hope this made sense.
I'm NOT dogmatic about it, I'm just trying to digest a LOT of previous argument into a short, explicit little blurb. . .