Why do some radio stations speed up their music?

There's always one radio station no matter where I am that plays popular music, but speeds up all the songs by half a heartbeat. It's not part of a DJ mix, and there are other stations that play the same songs at the correct tempo. What's the reason for this?
Some radio stations speed up their music to save time [1]. This is done to enable the station to fit more content, including advertisements, within the hour [2]. However, some stations may speed up songs to increase the energy [2]. Time stretching can be used to overcome issues where elements, such as ads and inserts, are added or removed from shows that have already been recorded [3].
Some radio stations speed up their music to sound more exciting compared to other stations [1]. It is similar to how some stations try to be louder than the others to make their station sound better [2]. In the USA, some stations would modify their turntables to run around 2-3% fast [2]. Nowadays, the reason radio stations speed up their music is to include more content, such as ads, within the hour [4].