How often should you roll stress?
I've been reading the one-shot adventure Overrun (I'll try to keep things spoiler free), and I realized that I'm unsure of how often to roll stress? Do you roll for every encounter? How about just the first time encounter? Is there some guidelines of when and where to roll?
STRESSFUL SITUATIONS, on p. 229 of the core rulebook, does not mention the frequency of stress rolls, only the kinds of things that might give stress and the stress damage they might inflict.