Yes, the delay does indeed seem to be taking effect. When increasing the delay it takes much more time to execute the steps, other than that I notice no difference. Except, that the beeping sound maybe changes just a little.
Actually, before I had a raspberry pi 4 where I used the same focuser setup, just with the astroberry focuser driver, if that helps.. It worked after I played a little with the enable pin, since the driver is not made for the DRV8825.