Definitely YES. If remember correctly, special encounters in original Fallout games were totaly random and could be found everywhere on the WM.
I suggest they can be found anywhere at any time with equal chance or smaller as now and infinite times per one char. This way the special encs are tied to normal gameplay and don't need to be abused.
When a new character is created, squares with each treasure are randomly chosen.So basically locations of treasures would be static, but different for each character.
Actually I think I have one char that got it two times.