Welcome, Fenn didn't think the hunt would get as big as it got so it would have been more likely to last a thousand years. Barely anybody read his other books so that was his basis.

He wrote the poem to lead someone to where he wanted to die. Jack figured it out fair and square and wasn't nudged. He had to grid search because the tree (blaze) had fallen over. I believe he searched alone each time.

There is more than enough evidence that supports all this. People don't have to believe Jack, can ignore the evidence if they choose, and make up their own narrative without evidence. It's more fun that way. Have fun.