BMW CCV are used because the intake is lower than the valve cover IMO.
I ran a CCV delete on my 02 X5's without a catch can.
IMO when we do a CCV replacement hose etc we overlook the dipstick drain.
After some time that drain line builds up with carbon deposits and oil, restricting the flow.
I've seen on some forums that people replaced their CCV system and are still blowing white smoke. (cold weather)
Just a thought when we leave our vehicles overnight (colder weather) the moisture in the air will condense on top of the oil in the engine. When you start the engine and check the oil filler you'll see Mayo. With the Mayo in the system and the dipstick drain line restricted the oil/mayo will start to back up into the CCv and then be sucked into the intake.
Also, a slowly running drain line will give the oil time to cool and capture more moisture and freeze the dipstick drain.
The catch can method (colder weather) will catch more condensate IMO.