[BoomerSooner]

There is one case where tacking yardage on to the end of the run may not be favorable to the offense:

Line to gain is the opponents 20 yard line. Down and distance to go don't matter at this point of the example. The offense makes the line to gain and is tackled at the 18 yard line, and the defense is flagged for a personal foul face mask. When the clock is stopped for penalty enforcement, there is 3:00 remaining in the game and the offense is up by 1 point. In this case, there is enough time that the offense cannot run out the clock without getting a first down, but the penalty if accepted would result in half the distance to the goal (1st and goal from the 9) and the offense cannot run out the clock because they will score (TD or FG) or have a turnover (on downs or otherwise) before the clock expires. If the offense scores, the score differential will still be just 1 score unless the offense makes a 2 point conversion (which they would be unlikely to attempt unless they can't make a kick to save their lives). There aren't many, but some coaches are smart enough to realize that they are better off letting the offense score in that situation and trying to tie the game with 2:00 or more on the clock than trying to make a stop then go the length of the field with 0:20. There are also some coaches that coach their offenses not to score in those situations if a first down will allow them to run out the clock. I'm a proponent of the let them score, but not a fan of the don't score strategy, but regardless, automatically enforcing the penalty takes that piece of strategy away from the offense.

Ultimately my point is be careful of doing anything automatically. While I generally agree with Rich's position, I also hold the position that doing stuff in a rote/automatic manner without thinking about it can be dangerous. I think there are some guys that have been around long enough to get these nuances, and others don't and would benefit from not putting things on auto-pilot.