I was just saying to someone the other day (and then explaining what I meant by 'Hit Factory') that it seems pop music has taken a major swing in this direction very recently, not to say that there hasn't always been an element of it through the decades, as you say, but in the last five or six years the whole "Change a word, get a third" thing seems to have become very popular.
We were discussing the fact that someone like Drake or JBeeb or Katy Perry can somehow release two albums a year and have four singles in the charts at a time, and while digital downloads obviously play a part in chart positions and the release of tracks, the sheer amount of stuff they're putting out is u deniably down to the fact that they don't have to sit around for six months writing it, there is a team of people paid handsomely by the record company who do it "Brill Building" style all year round.
Katy Perry goes in the studio and says "Hmm, I don't really like 'oh, oh, baby, baby, oh', can I change that to 'baby, baby, oh, oh, oh'?" - written by [X], [Y], [Z], and Katy Perry....