If there are no missing steps, then the RPM will depend only on the pulse rate.
The current (within limits) determine the torque and the power (current and RPM both)
If the motor is starting from rest, most of the power goes into the rotor inertia (KE of the rotor). If there is insufficient current, it will miss some steps.
If the motor is going to stop, you need to have similar consideration else it will again miss some steps.
Accel /Decel cannot be done with a fixed pulse freq and no missed steps. For low pulse rate this may be less important.
Basically you need to get to speed (or stop) within one single pulse. OP is concerned about missing steps.