the more flushes the better, i'll be doing mine again next week, it's third so far and i still keep getting the residue on the cap... I do remember seeing a post on this site a while back for a coolent filter that connects just before the thermostat on the top rad hose... I think Scotty may have one already, ask him about it as it may save on many flushes....I should get one as well...
let me know what you come up with....