Depending on your power level the standard breather system is fine if the pipes are clear, the one way valve is working and there are no leaks (filter casing splitting is common for example).

Upgrading to a Bailey or similar system is only needed if your running big enough power to have increased crank case pressure to the point where the stock setup cannot handle it.

I do agree with Jano though that venting your oily fumes back into the engine is not ideal (but it's not just MFI that does this, every car since the late 1960's recirculates it's crank case gasses and burns them as standard), strictly speaking a road car should not vent to atmosphere.

Chas you make a good point, understanding is far better than just blindly doing what you are told.... What's that old saying about a cliff and jumping off it! lol