I agree with everything you say here. But I don't see how it relates to the original point there are rules in the NFL that don't allow a team to go as fast as NCAA. There are no rule differences affecting the pace throughout the game and the clock stoppage issue at the end of a half would cause the offense to go faster in NFL than NCAA not slower.
One thing that prevents a fake injury near the end of a half in NCAA is the play clock status after an injury. At one time the defense could gain an advantage in time conservation. Let's say a play ended with 1:45 left in the 2nd quarter. The game clock continues to run and the play clock goes to 40 and starts. With 35 seconds left on the play clock a defender has "an injury" and the game clock is stopped with 1:40 left. At the time the rules set the game clock to 25 after an administrative stop like an injury or penalty administration. This would allow the defense to conserve 10 seconds on the game clock if they are trying to get the ball back. The rule was eventually changed to set the play clock to 40 seconds after a defensive injury regardless of time of game. It prevents the defense from gaining a time advantage from either a real or fake injury and likely reduced some of the fake injuries.
Not in terms of snaps - I guarantee you if you take a NFL team in a two minute situation at the end of the half or the end or the end of a game (let’s say no TO’s) and compare it to a college team in the same situation, the college team playing under the “stoppage after a first down” will execute more snaps than the NFL. It is the same for an entire game.
Example: watch the end of Rams/Bucs playoff game. 28 seconds left. Rams with no TO’s. Ball near mid field. Pass completed in play with 20 seconds. Stafford runs team downfield, spikes ball/ time left - 4 seconds. Time left for one play. So 16 seconds have elapse. In the college game, clock would stop. Spike would happen leaving as much as 15 second the clock. Enough time for two snaps, possibly three in a college game.
The end of half of the Alabama-Auburn game in 2019; does Auburn come remotely close to position to kick the FG, much less get the FG team on the field in the NFL? No - clock stoppage after the first down led to that and “additional snap(s)” (along with a stupid review).
Playing “fast” in college is about the number snaps a teams runs. When the clock has stopped after a first down and the offense is snapping the ball with 8-10 secs off the game clock versus in the NFL after 25 seconds into a game clock it makes a big difference. Those additional snaps at the end of a half or the end of the game make a huge difference in terms of fatigue.
Why don’t NFL run uptempo all the time? Ask Chip Kelly. The biggest advantages of uptempo at the college game is fatigue factor on your opponent (pace in terms of snaps), getting mismatches versus defense, and getting the defense misaligned or making a mistake. In most cases in the NFL there isn’t a strategic advantage to going uptempo an entire game. Periodically, yes. For an entire game, no. Most teams with veteran leadership on defense in the NFL can tell you what the offense is going to do based on personnel and formation before they even get a call from the DC.
Additionally the NFL games is more “down and distance” and personnel packages for those circumstances. And there is seemingly more emphasis on the “right players on the field for the right situation”.
Pace of play IS effected by clock stoppages in colleges game. The original poster is referencing “pace” in terms of plays run offensively and TIME OFF THE GAME CLOCK (not the play clock you keep alluding to). If there isn’t advantage in running those 10-15 extra snaps in a game, Riley, Huepel, Malzahn and others wouldn’t run it.
The fake injury stuff you see in college football is as much a factor of the number of plays being run as it is anything.