Conversation so far:
How did the critic Robert Hughes get started in his career?
The critic Robert Hughes, an aspiring artist and poet, abandoned his university endeavours to become first a cartoonist and then an art critic for the Sydney periodical The Observer.
What did the critic Robert Hughes do after working as an art critic for The Observer?
The critic Robert Hughes settled in London in 1965 and wrote for The Spectator, The Daily Telegraph, The Times, and The Observer, and contributed to the London version of Oz.
How long did the critic Robert Hughes work for Time magazine?
At some early point in his long career, more than three decades of it spent at TIME, Robert Hughes became the most famous art critic in the English-speaking world.
What did the critic Robert Hughes write for Time magazine?
In 1970 he was appointed art critic for TIME magazine and moved to New York, where he soon became an influential voice.
Who else did the critic Robert Hughes work for?
The critic Robert Hughes and Harold Hayes were recruited in 1978 to anchor the new ABC News newsmagazine 20/20.

Question: How long was he there?
Self-contained rewrite: How long was the critic Robert Hughes at ABC News newsmagazine 20/20?