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Tom Brady leads the New England Patriots against the Atlanta Falcons in Super Bowl LI. Getty

While many football fans can't wait for the Super Bowl to begin, there are millions more who can't wait for the game to end. An NFL game can last well over three hours and for some viewers it can feel more like an endurance test than an enjoyable TV experience.

The Super Bowl is expected to kick off at 6:39 p.m. ET. Though most NFL games tend to last about three hours and 20 minutes, the Super Bowl lasts a bit longer. There is a lengthy halftime show and an award ceremony that follows that includes the presentation of the Vince Lombardi Trophy to the owner and the Most Valuable Player award to the best player of the game.

Super Bowl TV coverage can expect to end after about four hours and that's if the game doesn't go into overtime. (Overtime is scheduled for 15 minutes, but its conclusion is indefinite because of a complex scoring system.)

In short, expect Super Bowl LI to end roughly around 10:20 p.m. ET and for Fox's Super Bowl coverage to be fully complete at about 10:50 p.m.

Many may wonder why some games last longer than others. If the game is close there is a better chance of the game lasting longer than if it's one-sided. The main reason has to do whether teams plan to use timeouts and run specific plays with the strategy of preserving time.

If the game is a blowout, the team that is leading will probably not use all of their second half timeouts. Also, should the team that is leading have possession of the ball in the final two minutes, they can "take a knee" -- a play that involves the quarterback kneeling after accepting the ball from the center so as to keep the clock moving.

Since the New England Patriots and Atlanta Falcons are two high-scoring teams, Super Bowl LI might last a bit longer than other Super Bowls. The two teams will likely have a high volume of scoring plays, which means the clock will stop more often.

Also, the game is expected to be close, according to betting sites. The Patriots are favored to win by just three points.

After the Super Bowl, Fox will air "24: Legacy," a one-hour action-drama program that is a spin-off of the popular "24" program that ran from 2001 to 2010.