DFROBOT DR 10023 Motor Shield

Hi I am a new member with my first question. I have the above motor shield sitting on an Arduino UNO, and just got it to drive one stepper motor. I have my own code for later, but for now I am using the sample code given in the info sheet for the motor shield. There is a note stating that I can vary the motor speed within the code, so I have been experimenting with the delay in microseconds. To get the motor to crawl I am using max microstep (1/32) and 3000 microsecond delay. Please could someone advise if I am on the right path for motor speed control?
Phil Harding