Used to be, winning 20 games was a sign of a successful season. Still is to some extent, especially for some more than others.
For premier programs, however, a 20-win season is a pleasant signpost, a marker of achievement on the path to annual assurance of greater capabilities.
In this era of elongated schedules, 30 wins is an ultimate ratifying standard for national championship contenders. Elite programs reach those heights with some regularity, none more often than Duke.
In this century the Blue Devils achieved 30 or more wins 10 times in the 21 seasons this century, nearly every other chance they got.