To me it is not likely anyone who has, even if it were true that they had "been to Heaven [or] Hell", were put through the full reality of what it will be like. But I am extremely skeptical of such accounts —not doubting the sincerity of the person to whom something happened, but the interpretation they put to it.
Such things have happened to me, perspective-changing things, one was a vision or something, many many years ago, and it still sticks with me but without the urgency that I had at first, concerning the horror of sin and its effects on God's creation —not just a blight but a monstrosity, an open wound, lethal against the very existence of the whole universe, but for the power of God. But it was for me, not a proclamation for the world to hear. It is not my gospel.
A side comment: I like to think, in 2 Corinthians 12:4, "that he was caught away to the paradise, and heard unutterable sayings, that it is not possible for man to speak." that it may well be that there is no way to even be able to say what he heard, or to make them make sense to this temporal economy of existence or to a mere human mind —not quite how some versions give the implication that he would but he was commanded not to. I certainly find myself unable to relate what I saw in any worthy comprehensible way.