To clear it up a bit....
If you correctly want to ventilate your engine (I speak about engines over the standard Volume and enough horsepower), you have to plug your valve covers, your standard oil breather tower connection and maybe your fuel pump cover, if possible. These 4 hoses will be plugged to a box with at least six openings.
As you can see, the four hoses are there to vent the engine, the oil spray and dust is kept inside the box, there's a small drilled metal piece inside to seperate the oil and the pressed out air. The air is sucked through the top openings of the box through hoses into the carbs, where it is again burned. This system makes sense, because if you build higher volume/hp engines, that naturally produces more energy through more power, you have to route the bigger amount of compressed air out of the crankcase. The original opening isn't enough!
In the history of the beetle engine, err, to be correct, of EVERY engine, you'll see, that a crankcase ventilation is used everytime (we speak about normally aspirated 4-stroke engines
). The gases inside the case, that are compressed and pushed/pulled through the case, have to go somewhere. If there wouldn't be an opening, where it can leave, the gases would leave the case through the easiest opening, on a beetle engine that would be the crank pulley oil drain opening, or the sealing ring at the flywheel. Emission control makes it, that these gases have to be burned, because they are pretty toxic! Before this law, engines could blow-by everywhere to the atmosphere (remember the rubber opening at the end of the old oil fillers on the beetle, long pipe). You could even use small K&N air cleaners on the top openings of the box, to route the air to the atmosphere, but after a while, the oil gases will drip out of it and it'll look ugly!
What you wanted to have is a faster oil-return from the heads. When you plug hoses or pipes from the heads to the sump, you'll have a more constant oil-pressure in curves and under high revs. Every VW boxer with a high volume pump has the problem, that the oil is running back into the sump much too slow, after it was pressed through the pushrods into the heads. Believe me, if you run an engine under full load, high rpms, shut it off, run to a valve cover, plug it off and you've got a half Liter of oil on the road, when you're fast enough! (I tested that with a plug in the valve cover) That's a common problum and occurs only under high rpm/load, so don't mind of, just vent your engine correctly, that's it!