I was given a rear rim once and it had a campy freehub, decided to unlace it and rebuild it with a shimano hub so I could run it, the hub flanges were the same sizes, so I just said what the hell I'll reuse the spokes, few months later I started blowing spokes. I didnt know the original mileage on the wheel before i got it, but the spokes looked ok.
So after that I always kinda have it in the back of my mind about reusing spokes, I don't think it would be a bad idea to at least sort them so the pulling spokes stay pulling spokes and vice versa.