I don't understand exactly what you are talking about, but if you are talking and thinking about the chinese controllers, i have to clarify that-if the spindle is not a servo motor but HF spindle-then its best to make default frequency 10 000 and use SRO on panel. 2 benefits of that- its easier to adjust voltages on the VFD and thus the spindle speed at all speeds is more correct. Plus the override on the board i am testing is 10% 20%, etc, so 100 is easy to divide by 10 and usually 16000 rpm are programmed not 1575 rpm.
Hope that makes sense.

At the other hand its better to have an encoder. Especially if you don't like to change tools and do 2 or more different HSM operations with the same tool. Which will require to stop and change the tool and speed change. But if an encoder is fitted, then you could cheat by stop. change nothing but speed automatically from program and then continue with another/ the same actually/ tool. Recently i am doing quite a lot of that. Still the stupid way though.