On book acquisition

The last three weeks seem to have vindicated my book-buying habits: I never know when I'll want a pointless detective novel/ a mid-list SFF/ a Chinese mystery/ something light (all senses of the word) and forgettable/ so better grab this now. Except it transpires that these are what I want when laid low for weeks by a multi-symptomed bug, and how often do I get those? Once a decade, apparently: and ten years ago it was a deep incision in the abdomen causing my symptoms, not a bug at all.

Which means I should change my buying/ acquiring habits from 'You never know when I'll want this' to 'Do I want this now?' I still have twenty years of unread books around here, should I find myself bookless; and my personal nightmare scenario of 'I want this specific kind of book right now and I don't have it!!!' has so far proved a chimera.
( But a pile of forgettable books has been disposed of, and will go out on the lawn when there's some lawn for them to go out on )