Put another way, NCAA/NFL games, with all their commercials, etc., are generally +/-195min long. That said, in theory, since a HS game is -25% shorter, it (again, in theory) should only last about 146min.
Sadly though HS games are becoming about +/-180min, or only -8% shorter. - with no commercials too.
NFL games actually average just under 2:57. NCAA games (FCS) are averaging about 3:07, although many stretch to 3:20 or more.
In 14 years where I have kept track of all of our games, no game that was not weather delayed EVER broke the 3:00 mark. We came close this year for the first time, in a game where there were over 40 fouls called.
NFL halftime: 12 minutes. And that's not when the teams are called back onto the field. When the clock hits zero and is reset, the ball is handed to the kicker. And the halftime clock starts seconds after the second quarter ends.
College halftime: Usually 20 minutes. Again, the clock starts almost immediately, and when it hits zero, whistles blow and teams line up.
HS halftime (at least here): Officials wait until both teams are off the field, then they start a 20 minute halftime clock. When the 20 minutes is up, another 3 minutes is put on the clock. When the 3 minutes are up, the teams leave their "mandatory warmup" and head to the bench. The officials give them 30 seconds or so to talk, then start blowing their whistles to get them on the field. Teams huddle on the sideline, and finally get out on the field. Officials count players and hand the ball to the kicker. Then the R checks with each official by hand signal, and then the RFP is blown. Total time from end of last play of 2nd quarter: about 26 minutes.
Add to that, time between quarters is usually closer to 2 minutes than 1. Time after scores is always closer to two (or longer) minutes than 1. Ball goes OOB, and officials worry about keeping THAT ball in play instead of grabbing one from a ball boy and setting the new ball. Time from a runner going OOB to the RFP is closer to 25 seconds, when it should be 12.
If there were more plays going OOB or more incomplete passes, then we would be running more offensive plays per game. The average number of plays we run per game has not changed by more than 2% in 14 years (from 54 to 55).
You want faster games (which I don't think are necessary)?
Shorten halftime to 12 or 15 minutes.
Eliminate the mandatory 3 minute warmup.
Clean up mechanics! That includes:
- Starting the halftime clock when the half ends
- One minute time outs
- One minute after a score
- RFP in 12 seconds after the play ends
- Have the teams on the field and ready to go when the halftime clock hits zero
- If the ball is incomplete or goes OOB, grab a new ball and get it to the U. Let ball boys chase balls.
The pace of the game is MUCH more determined by the officials than by the style of offense run by the teams, or changing timing rules.