One of the biggest myths about wine is that it starts to fall apart the instant we open the bottle. Sure, a really old wine may gasp and die as soon as it touches air, but how often are we opening one of those? The maxim that oxygen is the enemy of wine, or that wine really wants to turn to vinegar, is irrelevant to us in our daily consumption of wine, because the decay doesn’t happen that fast.

And that’s a good thing, because many of us do not finish a bottle every evening. I hear this all the time: One spouse drinks beer, the other prefers wine. Or a wine lover lives alone, but still wants to enjoy a glass or two with dinner. Some people show remarkable restraint in not finishing a bottle in a single sitting.

If that’s you, the wine industry has some gadgets it would like to sell you. From cans of inert gas (nitrogen or argon) that you squirt into the bottle to blanket the leftover wine and protect it from oxygen, to the popular Vacu Vin, rubber stoppers and a pump that allow you to create a vacuum that protects the wine for several days, these products offer you peace of mind that your leftover wine will be as pristine when you return to it as it was when you first opened it.

I wrote about several of these gizmos a few years ago, including the Coravin, an elaborate vampiric device favored by collectors that sucks a sample of wine through the cork, filling the resulting void with argon gas to protect the wine. This way you can drink the wine, glass by glass over time, without ever pulling the cork.

The Vacu Vin has been my favorite. It’s easy to use, and the slight hiss when I pull the rubber stopper from the bottle is a reassuring sign that the vacuum has indeed protected the wine. But lately I’ve questioned whether even this simple step is necessary. I’ve found that merely resealing the bottle with its original cork or screw cap works perfectly well in protecting the wine, at least for several days. This is true whether I leave the wine on my kitchen counter or stick it in the refrigerator. Wines with screw caps, which create a tight seal, can last for weeks and still be good.

There’s a caveat: The wine needs to be good to start with. A strong, healthy wine will not only survive a few days after opening, but might even improve. This is a very informal, unscientific test I use to evaluate wines to recommend in this column. A well-made wine that tastes as good or better two or three days after opening as it did when it was first opened is demonstrating its quality. Poorly made wines tend to fall apart and accentuate their flaws.

This is another reason to search out quality wines and not settle for the cheapest. There’s no minimum price level that guarantees quality, unfortunately. We need to find the good wines ourselves — another reason to consult your local retailer.

Although the wine industry would love to sell us those gadgets to preserve a half-emptied bottle of wine, there are other options for those of us who just want a glass or two at dinner. Cans, pouches and boxed wines offer some flexibility in portion sizing, and better-quality wines are increasingly available in these formats. So the industry is finally packaging wine to match the way many people drink it.

More from Food: