If there's one downside to geeking out about spirits as a hobby, it's not only that you'll spend more at the bottle shop, but that you'll need a place to put things. A cupboard or shelf might work initially, but soon you'll find those bottles spreading across your counter like black mold.
I hope you'll allow me a short diversion into philosophy to explain the phenomenon—you'll see how it gets back to booze, I promise. Let's start with the Greek philosopher Zeno, who had a great job: sit around and troll other philosophers. As a result, he thought of a number of paradoxes that, while absurd in their conclusions, were nevertheless difficult to actually disprove logically or mathematically. If Zeno were a house pet, he would absolutely have been a cat, just pushing shit off ledges and watching the world burn.
Zeno's dichotomy paradox went like this: if you want to get to the end of something, you first need to reach the halfway point. Then, you need to reach the halfway point of what's left. And then the halfway point of the next remainder. Therefore, you can never actually reach the end of anything.
Here's the problem: Zeno seems to have it partially right when it comes to explaining the rapidly-expanding size of my home bar. It may take me about a month or two to hit the halfway point of a bottle. Then, another three months goes by before I drain the bottle to the 25% mark, mainly because I'm now rationing it. And after that point, the bottle lingers for several more months as I save it for only the moment where I want that spirit, and nothing else. I've drawn a visual representation below.
This isn't a problem if you have the space to put new bottles, or if you're fine with cultivating a neat collection of wonderful spirits that can be had at any time. But it is something to be aware of if you have, say, a kitchen table you actually want to use for eating. Shelf creep is real, and you will soon be awash in glass containers of various shapes and colors. You may eventually find yourself, as I did, looking up the weight ratings of your Ikea-purchased shelving units.
I'm betting this is true for you as well. Why am I so confident in that claim? It's because there's actually a psychological effect hampering our ability to drink a bottle we like down to the end.
We're fighting against what may be an evolved instinct called loss aversion. As Nobel Prize winning psychologist Daniel Kahneman says very succinctly, "Giving something up is more painful than getting something is pleasurable." Simply put, we feel losses twice as powerfully as we feel gains. Having the last centimeter of liquid in a bottle forces us to confront a loss. The more valuable the hooch, the larger our instinct becomes to "protect" it by, oddly enough, not drinking it.
The best advice I can give is a Shia LeBouf-like "Do it!" You aren't a historian. You're not a liquor archivist. The bottle of Talisker 10 or Hendrick's on your shelf doesn't warrant conservation status. When you run out of it, there will be more. So if you see a bottle that's getting to the red line, have the courage to move it to the front of the shelf rather than the back. Treat yourself and drink what you like.
The other alternative is to give away what you don't love and seems to be lingering out of spite. Most of us have another drinking buddy or two. The next time you see that person, hand them the half-empty bottle and say, "I gave this a chance, and I don't love it, so it's yours if you want it." Often, I find that the hang-ups I have with a particular bottle tend to be a little idiosyncratic and aren't shared by my two most liquor-savvy friends. So away it can go. Chances are they'll like it a lot better at the price of free.
Past that, there are a lot of ways to try something without having to pay for a full 750mL bottle. A bar with a good selection is a great asset: even if you're overpaying, a $12 pour can save you from bringing home another fifth of liquor that sits around the house for the next three years. I also am quite partial to miniatures for the same reason, although sometimes it's difficult to find a store with a good selection of them.
All in all, stare down your instincts to be the lord protector of every mid-grade bottle of hooch that comes into the house. Finish off or give away a previous purchase if you don't love it before you buy something new. I'm just trying to save you from the day when you can't take two steps in the house without tripping over a half-dozen spirit bottles. All with less than 2 ounces of liquid left in them.