My regular players are like the boiled from analogy. They're pretty good at recognizing a dangerous situation if they run into it, but they've bought the farm a few times with encounters that involve waves of monsters.
In my Verbosh campaign, both TPK's were the result of PC's doing something stupid, after they had a lot of information which should have caused them not to get into that situation, but they did anyway. They were sheepish after
Cpt John "Jack" Hammer 6A84A6 Age 22 male Rifle-1 SMG-1 Grav Vehicle-1 Tracked Vehicle-1 Gambling-1 Leader-1