Wall openings size to avoid attacks against wall

[zOldBulldog]

I built a defensive wall pattern based on some of the "tested designs" that has 1-wide openings with the intent that it would take minimum assaults while slowind down the approach.

This worked extremely well against all assaults until I got a wave of large spitters that stayed back and just spit at the wall out of range of my lasers and flamethrowers. Luckily I was around and had a tank.

Was my mistake that the openings are only 1-wide? Will 2-wide stop the spitter attacks to the wall?

Or has the enemy behavior changed and I now need a different design?