I would bet not one single person EVER did more than 5 domestic trips pre 117. Sure international trips worked....I'm not even sure if the 30 in 7 block hour limit applied to international flying. As far as domestic flying goes, you could not back up two 4 days in a row pre 117 because you would almost always run into the 30 in 7 violation. The fact you don't know this tells me you never flew 121 for an airline pre 117. Did you?