College football has a significant variance vs NFL in the frequency of scoring patterns/great or poor play/unpredictability due to the nature of who's playing (college kids,conference quality, etc)
A significant percentage of college games are also very high scoring, which skews favor onto over bets. The purpose of this model is to eliminate the human element of favoring one side and making the play based on math, fundamentals, and taking advantage of the line movement on the total
NFL ending totals and scoring sequences have remained quite steady throughout the years. And most NFL totals will always be close to or right at a number which is one of the key numbers. Crossing the key number quickly is the ultimate indicator, and in a college total...you may never even approach one.
It is fairly ucommon to find college games with a total less then 50, as most of them creep up into mid 50's or higher. You have more chances in a 40's type total to cross multiple key numbers.