I have never changed out any run bedding, just added some as needed.
Tho after almost ten years, the ground level has risen enough that I should probably remove some.
I keep about 2-3", no need for more.
I do not, I doubt it.
Plus you need space to store a huge pile out of the way.
IMO it's the perfect material for long term cold composting of poops in a run.
Smaller more delicate organic and wood products disappear much faster.
Deal with any drainage issues now while building coop and run.
Coarse wood chipping, from a tree trimmer, is the best long term solution for run bedding, IMO.
It won't last long tho, and may become a stinky anaerobic mess.