It was the same in Peak Cavern's entrance chamber (The Vestibule) a number of years ago. Everyone "knew" all the avens had been climbed but no-one could say what was at the top, or quote any reference (other than isolated Puttrell writings). So we had a systematic effort to climb them all, finding various new passages in the process. Several certainly hadn't ever been climbed before.
It's the only way to be absolutely certain - the important thing being to publish the findings. Otherwise, a decade or two in the future, cavers will be asking exactly the same questions!