Anyone know if a saddle's setback remains the same, regardless of the saddle's length? (270mm, 275mm, 290mm, etc., long saddles)

Saddle setback is the distance from the center of the BB to the nose of the saddle, measured horizontally.

In other words:
If you normally run a 5cm setback with a saddle that measures 270mm long, would that value change when running a saddle that's 290mm long? Would a longer saddle change your saddles setback, or, is setback ONLY governed by the saddles inital shape?


Thanks