Though football games can last up to 4 hours, the ball is typically in play for only 11 minutes, according to a 2013 article in the Wall Street Journal. Around 56% of the game on TV is devoted to replays.
Research for the same article found that in an NFL game, as many as 75 minutes, or about 60% of total TV air time (excluding commercials), is spent on shots of players standing on the line of scrimmage, huddling, or just walking around between snaps. In addition, cheerleaders are on TV for only about 3 seconds, while coaches and referees receive around 7% of the face time in a game.
In the 1930s, NFL game telecasts were just a constant feed of the field. Instant replay became commonplace in the mid-1960s, which helped fill the idle moments of the game. By the 1990s, some football broadcasts showed about 100 replays per game.
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