(from max martin's wikipedia)
The traditional division of work in the record industry often has the artist or songwriter writing the songs and then hiring a producer to help shape the sound. But at Cheiron, it was the other way around; the producers wrote the songs, played the instruments, and engineered and mixed the recordings, and the artist was only brought in near the end of the process to do the vocals. For example, on Britney Spears's second album Oops!… I Did It Again (2000), Cheiron had already written seven songs and had proceeded to record the layers of music before Britney even arrived at the studios in early November 1999. It took her only one week to do the vocals. Martin and his team worked more like a band that alternated singers. Martin explained his working method:

I want to be part of every note, every single moment going on in the studio. I want nothing forgotten, I want nothing missed. I'm a perfectionist. The producer should decide what kind of music is being made, what it's going to sound like–all of it, the why, when and how.[61] – LA Times, 6/05/00