Efficiency of changing blank wit spaces to colored with runners

[swimj]

On two spawn maps, generally yes, I would do this if there's no other big threats. Forces your opponent to devote 2 units to that wit space (1 to kill runner, another to take it back).

On one spawn maps, it really depends. Having good vision is really important and sacrificing a runner to take that wit space means you will either lose vision or have to spawn another runner. Sometimes you don't have that luxury.