PTO Engagement

Just got my first zero turn.



Can somebody explain why most brands (that I know of ) instruct to engage and disengage PTO at 1/2 or greater throttle?



Logic tells me to engage at idle and slowly increase RPM to minimize shock to the drive train.



I would think engaging at a high RPM would be a sudden jolt to components.



On my tractor i engage at idle to prevent undue torque to PTO shaft and implement.



I am really lost on this.



Thanks