there are 2 oil feeds to the phase adjuster from the final (closest to the phase shifter) cam bearing. If oil pressur eis allowed through one feed, then the shifter turns one way, if oil pressure is allowed via the second feed, it turns the other way. It is either on or off - one way or the other. there is no varition available.
control of the oil flow is via a solenoid plunger in the head (you can see it if you remove the plastic cover over the engine - it is next to no. 4 plug .
this is activated by applying 12 volts to it.
In normal use the cam is de-phased at idle, as soon as you accelerate 12volts is applied to the solenoid lifting the plunger and opening the second oil feed (also closing the first), the cam is then phased.
the phase shifter operates from 1200 rpm, the only time dephasing occurs is on the overun or extremely light throttle, it would appear to be purely an emissions / economy device only.
Hope that helps you Sir.
Joe.