And as ex smoker, I find it interesting it's not the smoking itself that was 'stress reducing' for me. But those 5 minutes I would make free for myself to do nothing (smoke) and just think.
I once read that smoking is a bit akin to a guided breathing exercise in that way - during those 5 minutes you breathe consciously and in a more controlled manner than usual.
I don’t know if its actually true but it always made sense to me.