I actually did end up running out of time once as a stupid character in the game. I actually stupidly ended up exploring the wrong side of the overworld and picking up all these cool items in random encounters (because I had high luck) then only to discover I had 3 days left. I ended up reverting back to an old save, without a couple of the cool things I picked up. So it will happen if you are stupid like me...and my fallout character.