I don't know that
challenging is the word.
My experience in Cornwall in the 70s was that the little oral information available locally frequently didn't match sources like Dines and Ham Jenks, which is the main written body of information. It was, quite simply, incorrect and insufficient for internal verification.
Combe Down was the same. There were various accounts of being able to go in one entrance and come out another, but the fact of the matter was that you went down more-or-less any open entrance and wandered around long enough, you might come out pretty much anywhere else.
Obvious cart-gate entrances, clearly visible as infills in the stone-work of retaining walls, were entirely forgotten. At least two properties had been converted from stables within the past fifteen years or so, both with such obvious entrances adjacent, yet no knowledge of them seemed to be preserved.
There was a persistent story relating to a local pub, which had an access into the mine below the cellar, used as a private lounge for out-of-hours drinking. This was attributed in one version to a pub which is actually still open, but certainly in that case was quite untrue.
One outlying area to the South-East was rumoured to have a now-lost entrance, but we couldn't identify from the underground survey where it might have been.
Frankly, if such canards could be repeated in an area with free walk-in access within the past ten years, and occasional pillar-robbing taking place until the 1960s at least, all within an area you could walk round in less than 45 minutes, it doesn't give much confidence in the oral information available.
''the stopes soared beyond the range of our caplamps' - David Bick...... How times change .... oh, I don't know, I've still got a lamp like that.