I still don't really understand what hint brushes are and how they work.
I've found hint brushes largely not very useful, yet some people swear by them. Every test map i've ever tried either yields negligible improvement or even a DECREASE in performance using them. I guess if you're uberl33t and can use them moar power to ya, but i gave up on them a long time ago1 = )
More important is to have a well-designed map with visblockers, or world brush barriers seperating the different areas of the map, and have it properly optimized:
3===>--Func_wall or func_illusionary complex brushes like pillars and detail/trim work.
3===>-Don't scale your textures too low--scaling them below 1.0 especially for large areas will boost your VIS time DRAMATICALLY, and make your wpoly soar to amazing(and unplayable) heights. I scale my textures as big as i can without them looking bad--rarely above 2.0-, but Stuff in the background can be scaled even bigger--between 2-4.0, sometimes higher depending how far the brushes will be from the player's sight.