Al Kooper would occasionally show up on Boston radio shows when he taught at Berklee.
He explained the songwriting royalty split to a caller, and the host, Howie Carr iirc, commented on how overpaid the wordsmiths were for some stupid song composed by Kooper.
Kooper commented, "And it took two of them to come up with those lyrics."
OTOH, I saw some documentary on The Go-Go's and the real musician in the group that wrote the early hits said the rest of the group saw how much money she was raking in, and decided that the group was going to be credited with "writing" any future Go-Go's songs from any of the members.
They were instructed to write new material to fill their albums. They were quite prolific when you consider how short lived their band was. Today they would be good to get to release 2 albums in 8 years