I understand your point there Le Fanu
For myself, I'm a new collector, and my measly 30 decks (not counting my spare Gildeds) aren't any where near being the sum of my collection desire
So yeah, I do have 3 copies of the Gilded. One I ruined by attempting to blacken in the heavily chipping edges with permanent marker -- it bleeds marker to this day when I use it. But I keep it anyway. One I riffle shuffle, and even though I've only used that deck 4 months, it looks like it's been through a war zone - the Gilded is NOT printed for longevity, methinks! But riffling is soothing to me, and I'm in a turmoil at this stage...then I have one that I got to NEVER be riffled, to be swirled around on a desk and cards chosen in that manner.. I actually feel like I need a backup of this deck yet. LOL
Then I had two Shadowscapes, (not counting the special edition which I admit is COLLECTION only) but traded one to TCO because he seemed so excited and thrilled about getting it. I was hesitant at first, because THIS deck also doesn't seem to be very sturdy -- when I hand-over-hand shuffle(which I'm not very good at) I sometimes ding the edges against each other and its edges are starting to split. So I'll be getting another backup. (I probably need to only swirl this deck too...) But when TCO seemed so excited, I asked my deck, Should I trade the spare to TCO...and got the 10 of Cups. That settled it! Off it went to find it's happiness
So, only one deck with backups at the moment, my Gilded. However I'm USING the backup (kinda..I am IDS'ing another deck now but if I weren't I'd be using it at least part time) so I need backup of the Gilded, plus one Collection deck. And if I decide to use any of my collection decks, then I need to get another collection one, at least...depending on how they wear as to whether I feel I need a backup.
Maybe I'm just hard on my cards..I TRY to treat them well (except my riffle deck which I know is just MEAN to them...) but either I've chosen particularly weak cardstocked decks, OR I'm gonna need a whole lot of backups, because they're not lasting... Maybe it's the laminate not really covering the edges so when I ding the card doing the hand-over-hand thing, they start to split...honestly I'm being careful too!
So to answer the question -- yes, I feel backups are necessary, at least one or ten of them...
~Yira