How much stainblock paint to use in bedroom and where?

I’m renovating my bedroom. On the north wall, there will be freestanding cabinets (wardrobes) against the wall; all interior walls except to the right (east) which is exterior. There’s no previous staining visible here. It’s some kind of masonry block material; not cinder block but vaguely similar. Should I put a coat of stainblock paint on the inside of the exterior wall, as a preventative measure, all over? The outside temperature here gets down to -10 C / +14 F. There’s no room to leave a large gap around the cabinets.

On a different part of the east wall, there is some discoloration due to previous mold. I’ve treated it, but I’m thinking of putting one coat of stainblock over the discoloration, then another coat over the whole wall. The same for the south wall. Both of these are exterior walls.

Is using more stainblock paint than is absolutely needed a problem?

(I’m going to keep this question open for at least 24 hours so everyone has a chance to answer.)