Mat_wireframe 1 or 2 most accurate?

[brisck1]

Ive been doing some optimisation tests recently and am a little concerned when I check my brushes are occuding in wireframe mode 1, its seems to show that the brushes are being drawn throughout the level all at once. by this I mean that if I look through a wall in a building I can see all the brushes outside that room no matter what. Now, recently by mistake I typed mat_wireframe 2 and it seems to show a different view of my level, and doesnt draw wireframes throughout the level whether you can see them or not.

What I want to know is, which is more accurate, and is there an easier way of assessing which brushes are being occluded or not?

Cheers
Rob