Unlike in my HS days, teams pretty much practice all summer now. Most schools participate in 7v7 drills, linemen competition, and team camps at colleges. Official practice began 8/1 in NC and they may scrimmage on the 10th day.
We have been starting Week 1 about the middle of August but this year it got pushed back to August 23rd. Playoff week 1 begins November 15th.
That gives us 12 weeks to play 10 games. Schools have the option to play an eleventh "endowment game" where they share the gate with the state endowment fund. It was popular 10 years or so ago but seems to be fading a bit in our area at least. Some years, based on the calendar, a team playing an endowment game was playing 11 straight weeks with no open date.