Display signs take 4 boards, that's half a cupboard or one crate. Why is a thing that just adds a primitive organization mechanic so resource heavy? It's ridiculous and just adds an unnecessary and disproportionate grind. I've literally never made one because it's just a nuisance.
Say you fit 18 cupboards along the wall in each floor of your tower, that's 90 cupboards or 720 boards to make display signs for each of those would take another 360 boards. That's 1080 boards.
And that's just one tower not including the basement. That's like what, roughly 45 logs using a metal saw? (Boards per log varies too much)
I think a much more reasonable recipe would be one board and one block.