It's usually a combination of both, along with timing and other key factors. This day and age just because a nikka is all over the radio doesn't mean they're gonna sell great. I'm in Houston and French Montana's single was all over the place, but he flopped. Juicy J was everywhere as well, will possibly flop. Not to mention cats fill their albums with features from artists that are superpopular...that shyt ain't gone help you tho bruh. People want artists that have their own identity, that stand out, and that can make music and hold their own as artists. If you got disposable ass singles that are all over the radio, whay am I gonna buy your album?