No, I get it. I dealt with vacuum system on dry sump and wet sump engines. Both race and equipment.
The higher the rpm, the more oil particles in the crankcase. The higher the compressive blow by, the more crank case pressure. Added together is worst case scenario.
Why / when does it restrict. Higher volume of air moving through the airhorn sucks in the crankcase air. It isn’t just turbo boost. All the n/a pickups and hummers see the same if not more oil in the intake than turbo. the airflowing creates the Venturi sucking in the air and the pressure in the crank case is still high- thats why the cdr was made on the n/a 6.2 &6.5 before turbos were ever added.
the added turbo simply creates more crankcase pressure because it induces more blow by even with brand new rings. Thats why they are different part numbers. The turbo ones regulate sooner than the non turbo ones because of this.
This is a dyno provable issue, we did it at work. I can tell you directly on a new engine bypassing the cdr is worth 3-4 ponies at 3500 rpm and same tains torque around 2300 rpm iirc. all stock engine. And it isn’t the “free fuel” of the oil burning because all clean intake manifold shows it. I can’t promise exact power gain and rpm, but I remember it was a tiny improvement on both ends. Rate of acceleration was also a tiny improvement but so little it was timer shown, not noticeable.
Something you could do to see it isn’t boost causing it warm up engine first then shut off- put a white t shirt over the hose opening and connect hose to trap a layer of the shirt. Block wastegate for no boost and start truck and immediately hold it at 3,000 rpm for a bit. Shut it down and inspect the oil on the shirt material. Do the same test low rpm. Do it with and without the cdr. Then again with the turbo and trap the gate to build 7 lbs. you’ll see it plain- higher rpm creates more oil to become drawn through than low rpm regardless of boost. Again, adding more boost (or more volume and lower boost pressure from bigger turbine) willhave more blowby and ramp up more oil loss.
the cdr works by volume of air drawn through it. When X amount occurs it closes more. Take an old one and adapt shop air compressor hose to it, then use a leaf blower. The volume of air going through the cdr creates pressure differential to close it.
I think we both agree it is wide open at idle and closes upper end- but I think you are saying it is boost related- incorrect. If boost then it would tap a hose from turbo output to control and there never would have been one on n/a engine.