Okay yeah the math makes sense now! And I'm guessing the apparent threat works to make for tense moments, actually. As in seeing one party member just faint will put the pressure on the rest.
Thanks for the clarification, it seems more harsh than it is, which is good!
Ah I actually missed the rolls only happening on opening doors actually – and that the doors staying open means no more random encounters in those rooms, makes sense now. That also alleviates the issue quite a bit.
Thank you for the thorough answer!