

Probability is just probability. What separates D&D from a video game is the flexibility of the players and the DM. Lateral thinking wins the day!
My advice? Review your players’ backstories and add in an unexpected ally who shows up just in time to deliver the solution, but at the cost of needing their help with something conveniently related to the main quest. Alternatively, encounter an NPC who, likewise, conveniently assists them out of a sticky spot in exchange for pursuing the main quest.







Personally, I view CR like the pirate code; they’re more like guidelines than rules.
I look for how much damage a monster can deal in one round. I try to simulate a planned combat encounter well before I throw it at my players to make sure it’s survivable if they’re smart.