I don't think so, unless you are at an extreme seat back position and wanting to extend it even further. The area where you can "rest" your sit bones on a saddle is around 2 cm long - enough to absorb a seat back error of +/- 1 cm. Then, with a small adaptation of the body you can absorb even a little bigger error.
The increment of 2-3 mm is valid for saddle height setting, because here you have very little reserve to absorb errors.