I presume this is for a petrol engine. In the case of a diesel, the ultimate result of the blow-by is the replacement of the diesel inthe intake by this oil. Enough of it causes the engine to run away. It feeds it self with oil and uses it as a fuel.
Not easy to to stop an engine like that once it starts feeding itself. You lift your foot and the it keeps on accelerating
. Leave it in 5th and tramp the brake till the smoke comes out the disks to make it stop. Only remedy is to go back to the 60's and release that pressure into the atmosphere.
What I did find helped, was to "T" from the tappet breather, back to the sump and to the outside. That way I could make the pressure and the vacuum you have between the top and the bottom of the piston moves the oil between these two points. There is still a certain amount that still needs to be released, but this is much less than just taking it from the tappet cover.
Oh, I feed my pressure back through the dip stick and then through a catchment bottle under the car and then to the atmosphere.
If I don't do this, my intake cakes up with that oil paste that every 25K km, I need to remove more than a beer mug of it from the inlet manifold. Just imagine what an inter cooler would look like.