It seems the higher the quality of the tape then the more problems we could encounter. I have several cheap L.P.type tapes which seem to have survived unchanged. (If you want hours of TV sound recorded via the accompanying crystal mic and noisy budgerigar!)
Later recordings on LR56 and similar professional tapes, in all shades from yellow thro' pink to various browns, all suffer in some degree to oxide flaking.
Perhaps the manufacturers applied more oxide in the manufacturing process.
No-one has mentioned the dreaded print through, lessened by storing tapes reverse wound. The theory being that any echo caused by adjacent modulation would be present as a pre-echo and has more chance of being hidden in the modulation. Think about it, it makes sense.

Between us all there must be a wealth of material still to be found: oh for the time.