I've made so many Hero Calls that have been wrong...

You should usually be 'wrong' when you hero call. As in, you should expect to lose the pot far more often than you win it. Otherwise it is not a hero call. If you only call on the river when you think you will win the pot at least 50% of the time then you are folding
way too much.
I kind of understand the idea behind this, and I have been right on occasions too, but without stats for live hands it's pretty hard to know the ratios and I remember far more where I was wrong and it was horribly expensive than those where I was right and won a big pot. I think I'm better than 50%, or at least I'd like to think that. I try to factor in the player's image/history and to think in terms of 'how often I need to be right compared to how often he's bluffing' which I guess is what you are referencing?