I was in the backroom for the entire 5 years I was there. I did nothing else. I was a backroom TM for the first year and a half, and then got backroom TL and did that for the next 3 and a half years. It varies from person to person I suppose. The way I act and think was more suited to the backroom (logical, strategic, tasky). I was not interested in any other position, and I was ill suited for them anyway, since I f***ing hate customers. YEAH I CALLED THEM CUSTOMERS. A guest is someone I invite in.
Anyway, I think if it's for your own workcenter and you are damned good at it, you'll probably be fine if the salaries like you. I've seen plenty of people though who were in one workcenter, and got a TL promotion to another workcenter that they knew little about (in terms of daily-experience details). It came down to having the right personality and a can-do attitude.
Of course though, it doesn't hurt to know more workcenters. Maybe a couple of other workcenters in depth, or at least enough knowledge about most workcenters to understand how they all fit together and depend on each other.