Unimpeded.

Ok, one master tape being used 100s of times over the years makes more sense than one tape just being used to record on 100s of times. Or one machine being used just 100s of times. If I was an editor, I would ask for a more clear delineation of the shifts of context between "two tape decks" "one set" and "assembled". Somebody like me who doesn't really speak English (or so it has been accused) can (and) did) get confused!

I saw them perform that, very special

I understood the statement in the way Kevin explained; deck=tape machine, set=(composite) tape. I don't find it surprising or unreasonable that the tape for a 70 year old and hugely successful album would have been accessed many times. Discogs lists 160 different releases of this album.