I think it's more to do with quality than success. Like, who'd honestly choose California Gurls if they knew Teenage Dream was just waiting to be released?
Plus, if she waits until after the album is released she immediately loses that massive first week debut. It's going to be much harder for her this time around to get the #1s after her album is out there. Roar's not going to sell an album, it's a big hit but as Linda Perry said, Roar's just microwave popcorn, who's going to want an album full of Roars?
Roar is no CG/IKAG. I know it isn't groundbreaking but being a empowerment anthem could sell PRISM Tbh