The benefits for using as many different photographers as possible outweigh the benefits of using only one.
As
PGPhotographic above said, models often develop a lot quicker than photographers do - largely because photography is such a massive learning curve - so you could feel yourself being "held back", or not progressing as quickly as you feel you could.
Having said that, theres nothing wrong with having a photographer who you work with regularly, maybe to experiment different styles and try different ideas.
Each photographer has different ideas, so in the end you'll end up with a varied portfolio which is key.
Thats a key point, shoots are often just as much about you as they are about the photographer - so make sure you get your ideas across, and make sure you benefit from the shoot too.
James