servo motor

Hi All,
Regular dc motors have straight iron core, while all the servo
motors I've (maybe not enough) have the iron core plaates set at an
agle, I think the reason for that is to help on the iron core
transition when coming in/out of the magnetic field right? thus
making positionig smoother than a regular dc motor with straight iron
core plates.
I'm wondering if a regular dc motor can be smooth as a servo motor.