Conversation so far:
What did Phil Hartman do in his early career?
Working alone as a graphic artist, Phil Hartman frequently amused himself with flights of voice fantasies.
What did Phil Hartman do as a graphic artist?
After graduating from California State University, Northridge with a degree in graphic arts, Phil Hartman designed album covers for bands including Poco and America.
What were the voices Phil Hartman did to amuse himself while working as a graphic artist?
Did Phil Hartman write anything else besides for The Groundlings?
Phil Hartman met comedian Paul Reubens and the two became friends, often collaborating on writing and comedic material. Together they developed The Pee-wee Herman Show.

Question: How long did he work on the show?
Self-contained rewrite: How long did Phil Hartman work on The Pee-wee Herman Show?