Well, being a bourbonista, my Scotch 'openings' are kind of an eclectic group, purchased in sort of an 'as-the-spirit-moves-me' approach. And, virtually every single malt I own is open, with backups only for Dalmore 12, Highland Park 12 and Aberlour A'Bunadh.
Also, comparatively, they are a relatively small group -- just seven different, standard-sized bottles vs. 40 or so open American straight whiskeys (bourbons and ryes).
But, even with bourbon, I open what I want, whether or not I have a backup. Many of the 150 or so bottles I have are one-of-a-kind, at least in my bunker; many are no longer even bottled. But even the 1954-distilled Very Old Fitzgerald BIB will be opened at some point (within the next year, I suspect). Backup will be whatever's left on the shelf.