I know this feeling. I use walkthroughs when I have the feeling that something like this has happened, but I try to not read any other parts of the walkthrough than what is relevant to my problem.OPENED A COMPLETELY NORMAL TREASURE CHEST HALFWAY ACROSS THE WORLD, AND IF YOU OPEN IT THE ITEM IS LOST FOREVER
I never use walkthroughs for fpses but I ususally look at the walkthrough for RPGs after I have finished the game once.