I think that myth died about a decade ago once the recruiting sites started posting legitimate times....
The myth that HS kids are running 4.3 and 4.4s is always funny.
For reference, here are some combine times the last 2 years of college backs as 21-22 year olds:
David Johnson 4.5
Melvin Gordon 4.52
Duke Johnson 4.54
Derrick Henry 4.54
Paul Perkins 4.54
Jay Ajayi 4.57
Alex Collins 4.59
Ameer Abdullah 4.6
TJ Yeldon 4.61
Maybe for some but look at all the threads about 40 times, there are people who still think 4.4s are common.