Unreal engine 1's BSP is the worst nightmare of all time. No matter what you do, your map is going to suffer from BSP holes and invisible walls. I don't know what math is behind it, but it's full of errors.
RGB was an attempt to make a map that is literally the color wheel itself.
I never made a map with a blockout first. That's one thing that I have to change. All my maps up to now were following the "I want to make a deathmatch map" philosophy were the only rule is to make something with many paths.