I do a 555 until I'm satisfied that everything is working. 5 miles, 50 miles, and then 500 miles on fresh rebuilds. 5 mile trips can be several times until I have all of the tuning done.
The object here is to simulate all driving conditions. Short trips, cold starts, hot starts, longer one hour trips, high speed interstate driving, around town, stop and go driving, night time driving, and if I can, driving in the rain at night. If I can't find any problems during all of that driving, I call it ready to go.