Hi funding33,
The motion functions: MoveExp, Move, MoveRel, MoveAtVel, MoveRelAtVel, and Jog perform a WaitNextTimeSlice to avoid being interrupted while starting a new motion, but only while a previous motion is in progress and the new motion is being calculated (and blended). MoveExp is the only function that should be called at a rapid enough rate for it to matter. The other mentioned functions (other than MoveExp) should not be called continuously (not more often than every 4ms) as it takes some time for the new trajectory to be calculated and to begin to have an effect.
HTH
Regards