I have every setting turned all the way up speed/accel/jerk is only limited by the power limits on the steppers. In the firmware speed is set at 300mms same with on prusa slicer. I just added zeros to the accel and jerk both in firmware and in the slicer. It’s an ender 3 with an skr V2 Rev b board and a generic 2 into 1 hotend.
I’m not a huge fan of the way the documentation reccomends you test for the ringing. They basically change the tune +x amount every layer and you pick the best looking layer. Thus you know what cancelation frequency works. This is subjective. I prefer the klipper style where you actually measure the ringing in the print and enter the length of x rings per x mm over y speed.