Typically, high school football players are allowed to play no more than six quarters during any consecutive seven-day period. Some states, such as Minnesota, allow players to participate in all four quarters but play only eight games in a season, rather than 10.
Student players are likely to come into and out of play throughout a game, so many states afford the player the amount of time that would constitute three quarters. Player time limits exist to protect students from prolonged play, which might result in injury or concussion. Independent schools, or schools that are not state funded, may set their own limits on field-time eligibility for students. Quarter limitations may change post-regular season and in championship games.