Sometimes not even then.
Serious question:
Does Penn State football have a true rival?
They've been a very formidable program for about six decades, have been competing for national titles for five and have a few national championship trophies in their display case.
Nobody would consider them a flash in the pan, a poser or any other derogatory label one would give a program that thinks it's something that it isn't. Until about forty years ago Pitt was absolutely a rival and was always their last game of the season. One strange thing about that however was that there was only about a ten year span (mid 1970's to mid 1980's) when both were very good at the same time. From WWI through the early 1960's Pitt was the far superior program but basically once Paterno took over, PSU was very good while Pitt had a terrible decade, followed by a decade where they were as good as any school, followed by a lot of mediocrity.
Penn State football is a storied program that is among the best yet really doesn't have a rival. The same can be said about our basketball program.