There's no reason to drag out the old vertex tool every single time you make a wall, when figure 3 works just as well. Your third option is the best.
Example 1 said:Object.names.......Objects/Maxobjs..Memory./.Maxmem..Fullness.
------------.......---------------..---------------..--------.
brushsides..............60/65536.........480/524288...(.0.1%).
planes..................44/65536.........880/1310720..(.0.1%).
vertexes................61/65536.........732/786432...(.0.1%).
leafbrushes.............11/65536..........22/131072...(.0.0%).
edges..................116/256000........464/1024000..(.0.0%).
physics...............[variable]........3754/4194304..(.0.1%).
Example 2 said:Object.names.......Objects/Maxobjs..Memory./.Maxmem..Fullness.
------------.......---------------..---------------..--------.
brushsides..............72/65536.........576/524288...(.0.1%).
planes..................54/65536........1080/1310720..(.0.1%).
vertexes................49/65536.........588/786432...(.0.1%).
leafbrushes.............15/65536..........30/131072...(.0.0%).
edges..................106/256000........424/1024000..(.0.0%).
physics...............[variable]........3530/4194304..(.0.1%).
Example 3 said:Object.names.......Objects/Maxobjs..Memory./.Maxmem..Fullness.
------------.......---------------..---------------..--------.
brushsides..............60/65536.........480/524288...(.0.1%).
planes..................44/65536.........880/1310720..(.0.1%).
vertexes................51/65536.........612/786432...(.0.1%).
leafbrushes.............10/65536..........20/131072...(.0.0%).
edges..................109/256000........436/1024000..(.0.0%).
physics...............[variable]........3754/4194304..(.0.1%).
Well, i expect the diffirences to grow bigger but still have the balance the same between them. But on a side note. It does show that situation 1 is the worst to use, simply as 3 beats it. However, #2 and #3 combined seem to have all the ideal values together. So i think its about having a fine balance between them.But thats on a very small scale. I bet if you had lots of brushes it would be a different story.