meaning of "more often than not"


I read this sentence from an article about Pete Sampras.

“A rare splurge was to go to Vegas to play blackjack for a weekend,or to Peter Luger’s steakhouse in New York,which more often than not left him queasy because he wasn’t used to such rich food.”

“more often than not” means “often,almostly” ,right?

And why did the writer use such a long phrase rather than other simpler words?

Thanks ! :slight_smile:

It sounds nice. It somewhat suggests the unexpected nature of the unfortunate experience.