The goalpoasts for Nebraska have not moved with any head coach. Believe it or not, even Tom Osborne struggled to win the conference in his first 10 years.....even though he took over a program that had won back to back national championships. Those goalposts remain firmly in place.
(emphasis mine) On your point, Tom Osborne won the conference in his 3rd and 6th seasons while reeling off six consecutive Top 10 finishes and berths in the Sugar, Fiesta, and Orange bowls. Oklahoma won two national championships during this period. He also won the conference in his 9th and 10th (and 11th and 12th) years.
The first season in which Osborne's Huskers didn't finish in the Top 10 was his 17th.