Acts like Ke$ha, Rihanna, Justin Bieber and Katy Perry don't have any control
Britney had control on In The ZOne and Blackout eras, Circus was completely controlled, no wonder the quality downgrade
.
Artist like Beyonce, Shakira and Pink have huge control over their music
Taylor Swift also has control, becuase they let her do any song and it will still sell.
Christina and Miley had control, but they turned a huge flop, next album of both will be completely controlled.
Avril has control, but her label wants also control so she will end up like Kelly Clarkson