In some ways you could be right. 1 line of Mariah = 4 minutes of Duffy.
But in others there would perhaps be more mileage, say 1LoM = 8 minutes of Barry Manilow, or 1LoM = 10 minutes of high velocity techno hard core garage superhouse thingy heard via the ears of someone beside you listening to it on their ipod.
Still, could be worse, it could be the 30 seconds after the end of the ad-break during Loose Wimmin.