>> Keith says one or the other writes 90% of the song and the other contributes just a bit at the end. <<
actually that isn't what Keith says in that 1973 interview; he said it works that way sometimes,
and other times it works in other ways - which is about as deeply informative as the Glimmer Twins ever get
about their songwriting processes.
timeisonourside.com has a few good pages about it: [
www.timeisonourside.com]