I’ve heard all sorts of stories about how the networks both in North America and the UK back in the 1960s and 1970s chucked or taped over untold numbers of programs and how miraculously how some programs were recovered or saved. It really is heartbreaking to read about what ones were lost forever all in the name of conserving storage space or the naïve idea of videotape being reusable or copies intended for preservation being accidentally destroyed by some nameless idiot or even actors/production crew unions regarding the preservation and rerunning of programs a threat to their jobs.
This happened with videotape so much that the show Dr. Who had to put out a call to all with home video to find lost episodes. There were many.