In any case like this, you have to make a judgment about a person's character. In this case, I'd say he is serious, and that's why it is an expression of his tragic flaw.
By that I mean, Hamlet waffles. He genuinely intends to carry out his father's ghost's bidding, but he also genuinely doubts. Each time he has a change of heart, he means it, and that's what stalls him. Each one is real; each one is a problem.