I think that there should either be a) 3 wide walls, instead of 4, or b) both wall types, 3 and 4.
This is because in TPT the square brush goes in terms of 3, and it's hard to match with walls that go in terms of 4. It would be much easier to do things with a 3 wide wall, and I think it would help many builders out.
no,
wall system is meant to be 4X4 because yeah, it matches pressure mapping, if you want pressure+heat+indesctructible walls you can use
DMND
INSL
TTAN
as WALL that is 3 wide.
you could make the brush extend down and to the left of the starting pixel to create a 2x2, then 3x3, then 4x4 etc.