Quote ="secondstanza"Or if you bring someone with the intention of playing them 80 minutes you only need 1 back up. I suspect for example, Ben Hunt is backup to Cam Smith as I'm not seeing anyone else who would be suitable to play 9 and Hunt has played a fair bit thre this year.'"
Conversely someone like Roby can play hooker and loose forward and at a pinch scrum half.
It also allows rotation as well as extra cover in an important position for a side (hopefully) playing 7 games in 7 weeks against pretty tough opposition after a 37 week season.