How Many Episodes Should You Watch Before Quitting a TV Show? A Statistical Analysis
(www.statsignificant.com)
Jumping the shark was a—metaphorically and in one case literally—real thing that used to happen, back when 22 or more episodes were cranked out per season, leading eventually to there being no juice left to squeeze from the show’s premise, causing it to go off the rails. It doesn’t mean just a “decline in quality,” or at least it originally didn’t.