I use hint brushes like a bitch - far more often than area portals (which are damn useful, but are effectively a more powerful version of hints that come with an overhead-causing clipping trait). There's no harm in using hints frequently as, if you know what you are doing, you can almost always ensure you create a much neater BSP than VBSP would manage. Even though, at a basic level, they are used to create additional cuts in the BSP tree, I tend to use them to simplify it - adding a cut manually can save some horrible automatic cuts. For example, pretty much every window and doorway should have a hint covering each open side of it (but ensure the top, bottom and side faces have skip textures or sometimes they cause cuts that extend outwith the door boundaries!). By ensuring you have a clean BSP tree with neat and logical leafs, you can keep VVIS compile times down to an absolute minimum. My levels rarely take more than 10 seconds (but admittedly, rarely have wide open spaces) on VVIS because there are very few unnecessary leafs to complicate the calculations.