Conversation so far:
What was Irving Thalberg's role at Universal Studios?
Irving Thalberg was initially an office secretary at Universal Pictures' New York office.
What year was Irving Thalberg hired in the role of secretary at Universal Studios?
Irving Thalberg joined Universal Pictures in 1918.
Was Irving Thalberg ever promoted during his time with Universal?
Irving Thalberg later became personal secretary to the studio's founder and president, Carl Laemmle.
What did Irving Thalberg do after becoming Laemmle's secretary?
At age 20, Irving Thalberg became studio manager, responsible for immediately overseeing the nine ongoing film productions and nearly thirty scenarios then under development.
Was Irving Thalberg successful running the LA studio with Universal?
Biographer Bob Thomas writes that after three years at the studio, Irving Thalberg continually proved his value.

Question: How long did he keep this position?
Self-contained rewrite: How long did Irving Thalberg keep the position of studio manager with Universal?