Good guys of LOTR clueless?

[Maédhros]

But by no means were the good guys clueless. All they could do was act on the information that they had at any given time, which was necessarily incomplete.

Well, Gandalf knew that Bilbo had a ring that made him invisible and he didn't bother to find out more about it.
I doesn't get any more clueless than that! Why did he have to wait all that time for?

Also when Isildur took Sauron's ring, Elrond and Co. just said, well ok, and that was it.

And with Sauron believing that his ring was destroyed, if I recall correclty, in LOTR I have never read that Sauron said that (I don't think that I have seen Sauron having a dialogue in there). All that we have is the thoughts from the good guys about Sauron.
I believe that the good guys won from sheer luck. They didn't have a brilliant strategy planned. They knew that Sauron could not be defeated with armies and they could not use the ring against him. The good guys strategy was to have Frodo go and destroy the Ring, but he was unable to throw it into his little fire in Bag End.
What if Gollum instead of falling into the fire had run out and was taken over by a Nazgûl?