I'm digitizing master 1/4 track stereo tapes recorded on 3/5/71 & 3/1/73. They're Scotch 207 (one mil backcoated) and have been stored these almost 30 years in the living areas of the client's homes in relatively moderate environments. The stuff was stored tails out. I rewound them @ 30: barely any shedding occurred on either surface & absolutely these was NO squealing. They azimuthed and phased beautifully. David Yost and Nick Bodley (then at the Manhattan School Of Music) did superb recording on these.
So, perhaps we should consider specifying that tapes be stored in clothes closets...