"Sie liest jeweils eine Zeitung."
Why can't I say: "She reads from time to time a newspaper." if "jeweils" is also " from time to time" http://dict.tu-chemnitz.de/dings.cgi?lang=en&service=deen&opterrors=0&optpro=0&query=jeweils&iservice=&comment=&email=
That would imply that when she finishes one she picks up another. One at a time would mean that she doesn't read more than one simultaneously.