since it is not just unlikely that we'll ever have enough resources devoted ot double checking then perhaps we should just abandon it or now and concentrate on looking in the main active region for primes. Have any of the double check tests even reported a differeing residue? Sieveing between 1million and 5 million seems pointless. How is the double check ever going to catch up to that. And still i nthe mean time we may find more primes and the time spend sieving adn prping those ranges would just be additional waste.