The return test is not a quickie easy test.
Basically if your truck runs smooth and quiet, doesn't white smoke, doesn't leak fuel into the crankcase, starts fine and does not give you low rail pressure codes just drive and enjoy your truck. A good check of the system is weather or not the actual fuel rail pressure can match the desired fuel rail pressure when commanded up with the scan tool at idle. If it'll do that and doesn't have any problems I mentioned above it's healthy enough not to worry about it.