You use "for" here, but then use "etter" to say "klokka går sekund etter sekund." Can "for" and "etter" be used interchangeably in this case, or is there some difference?"
Minute by minute. time goes by minute by minute.(Tiden gaar minutt for minutt)
It is the title of a very good song by the Doobie Brothers. If you listen to the song, perhaps it will make more sense to you.