Btw i see some changes in the story be made as in to make Zack smarter, and im not that familiar with the game on my own (i played like 2 paths i think), but i think it would also make sense to leave some not smart decisions just to keep Zack being a human y'know? Like we dont usually always make the best decision in the moment and also ponder about how we could do this or that better after and such
And on some paths he does, and will.
However in the Brainwashed path, Zach being smart is very deliberate. It is a counterpoint to the sexist stereotype that men are idiots. It's also very plausible, because he's had time to think this plan through, and from watching true crime videos, he has a good enough idea of what not to do.
However there is a subtext that I think you missed. A big reason why Zach's plan is successful is because there are way bigger problems that what he's doing. A nearly empty office building. A security guard who doesn't really give a shit, and the fact that he was able to acquire a Re Education helmet at all.