Quote from josepezdj on September 4, 2013, 7:20 am

To be honest I always thought that was sort of a "guide" to make both, the "_logic" and the "_base" instances coincide perfectly... Take into account that those brushes are outside the map and after the compile they will simply be removed

Quote from Lpfreaky90 on September 4, 2013, 7:27 am

there are often skips in valve instances; probably to make it easier to move around or something.
Because they are deleted during vbsp (the first step in compiling)they don't serve any purpose except for aligning stuffs.