Conversation so far:
What did donovan do when Art Donovan left the nfl?
He published an autobiography, Fatso.
Was the autobiograpghy a hit?
CANNOTANSWER.
What did he do after the autobigraphy was published?
He was noted as a jovial and humorous person during his playing career and capitalized on that with television and speaking appearances.
Did he ever become a sports announcer?
He also appeared as a guest commentator at the WWF King of the Ring tournament in 1994.
What kind of television and speaking appearances did he make?
Donovan also appeared ten times on the Late Show with David Letterman, telling humorous stories about his old playing days and.
When did he retire?
CANNOTANSWER.
What shows did he do besides Letterman and WWF?
Donovan guest-starred in the Nickelodeon show The Adventures of Pete & Pete.

Question: Was that a one time guest appearance or multiple shows?
Self-contained rewrite: Was Art Donovan's appearance on The Adventures of Pete & Pete a one time guest appearance or multiple shows?