Yes I would also prefer that radios picked on Rihanna single and stuck with it but IDJ hasn't given adds dates to any of the songs besides Diamonds. They're being played yes, but because radios decided to play them on their own. This situation only goes to show that radio stations across different formats are eager to play new music from Rihanna. Without an official announcement they're picking whichever songs they feel more suited to their format.
Diamonds has too much airplay still. It won't do any good to release anything until it dies down within a month. Otherwise... She'll face another You Da One-situation.