I'm still not convinced buildings are worth going in for infantry, even if the building doesn't collapse in one turn. One big shot will still kill any weaker infantry.
If I had a Achileus Light Battle Armor with 3 life and 1 TMM and STL, for an average mech at medium range to hit it, (if I got this all right) it would be skill 4 + range 2 + TMM 1 + BA 1 + STL 1 = 9s to hit, which would likely take several shots before he goes down.
However, if I park that same BA in a building at medium range, now it's skill 4 - Immobile 4 + range 2. It's an automatic hit on a building at medium (or close) range. Yes, the building would absorb some damage (attacking units inside buildings), let's say 2 for a medium building. But that means the enemy only needs to shoot the building with 1 mech that can deal 5 damage at medium range, and it's instantly dead, guaranteed.
I get that it will make them impervious to lighter mechs with 2 or less damage, but now only 1 big hitter has to shoot, and there's not even a chance of the BA surviving. One could make the argument that now the strong enemy is not shooting mechs, but a guaranteed loss still doesn't sound palatable to me.
Am I understanding this correctly?