No, you basically said your sole criteria for measure whether a decision is a success is whether it works or not. There isn't even a grey area as to whether that statement is right or wrong.
Actually, I miss read your comment. I thought you asked is a three point shot always a great decision.
But to answer your question whether a three point shot is good every time it goes it, yes, it is.
Anytime a play works, it's a good play. The reason why people do what they do is because they think it's going to work. But that doesn't mean it's not risky.
Aren't we talking about risk here? It would be more risky to try something like that when you're up by three vs. up by seven. It would be more risky if you did it in the first quarter than if you did it in the fourth.
But guess what, if it works, it was a good decision. Results determine whether it's good or not. How else would you judge such a thing?