Be sure to mount the can as far from the engine as possible, in front of the radiator is ideal. You want the can as cold as possible to help the hot stuff condense and stay in the can, rather than remaining as a vapour and going all the way through the system.
Also, effective baffling and wire wool provide/Brillo pads etc provide more surface area on which matter can coalesce.
The problem with catch cans is that, even with 100% effective separation, you are still sending incombustible gas back into the cylinder and reducing the effective displacement of your engine. Also, that blowby is still warmer than ambient and can contribute to preignition. Oil vapour also promotes preignition.
For best engine cleanliness and best power and best economy, and either map out or blank off the EGR and do not direct PCV vapour to the inlet manifold.