Well, if it can play the next song that fits and belongs to the stage, then I guess its ok. For example, if mute city plays its original song, but then plays the car select song, then that seems alright. But if it switches to lets say a Mario song or just some music not related to the game, it kinda kills the origins and identity of the stage itself.
Personally, I prefer the way brawl did it by keeping the songs to the stages where it belongs and only play one song during battle.
Or even just leave it with just 1 song per stage