Running out the clock
In American football, each quarter of a game is measured with a 15-minute game clock, or 12-minute clock in many high school football codes and the German Football League. A team in possession of the lead and the ball will attempt to use up as much of the game clock as possible in order to bring the game to an end more quickly, thus denying the opposition another chance on offense.
NFL preseason
The exhibition season typically begins the first weekend of August with the Hall of Fame Game; though in some years it can be on the second weekend. Previous seasons have seen the American Bowl game held the last weekend of July. The first full schedule of exhibition games is held the following weekend. Most games are held on Thursday, Friday, or Saturday nights, with one nationally televised game each night of the week: NFL Network airs a Thursday game, CBS and Fox a Friday and Saturday night game each, NBC with Sunday night games, and ESPN a Monday night game. Unlike the regular season, CBS's and Fox's national exhibition game opponents are selected regardless of conference. Four full weekends of games are held. The fourth and final full week of exhibition games (fifth weekend overall) usually has teams playing exclusively on Thursday night (plus Friday, if any), with no national games. This allows teams a few extra days to prepare for the first week of the regular season. It also prevents conflict with the start of the regular seasons for high school and college football, allowing those venues to expand their first weekends' games from Thursday through Monday (Labor Day).