Her timing was serendipitous at Duke insomuch as she became head WBB coach there just as Coach K had completed the ascent of the Duke men and made them champions. I firmly believe the brand equity the men's program established for Duke basketball helped Gail build the women's program from scratch. It also doesn't hurt that Duke is an elite institution academically, where admission to the school and to get a free ride there is a big draw (a la Stanford and Northwestern).
Having said all of that, Gail did leverage what she had going for her and built another powerhouse program in Durham. The 1999 regional final was a shocking upset of Tennessee and a nice run to the championship game. Duke also came within a hair's breadth of winning it all in 2006 and was an entrant into the Final Four three other times. I do think she would have had even greater success than Coach P from 2007-08 to present.
However, you cannot overlook how much of a disaster she was at Texas. This was a program with some tradition, a great location, good academics (even if it isn't Duke), immense resources and facilities, etc. Yes, Gail had to pick up the rubble left by Jody Conradt, but Texas was still a place with all the things that should enable success. And her record was awful: 102-64 W-L record, a losing overall record in the Big XII, and no trips past the second round of the tourney (and only one trip TO the second round of the tourney, even). In short, her chances of success at Texas should have been as auspicious as at Duke, she was well compensated for it, and she failed miserably.
Her resume might have been HoF-worthy had she stayed at Duke, but as is, she's won 498 games with no NCs. That doesn't feel like a resume that writes a broadly-memorable chapter in the history of WCBB.