If it is only you drinking the wine everytime you open one, you should consider 375's (1/2 bottles) more or step up your drinking .
To answer your question, it comes down to the type of wine, the quality of the wine and your tolerance for what is "drinkable" after opening. For me, non fortified (Ports and other sweeties) wines go in the fridge and I pretty much have to finish the next day or I don't enjoy it at all. There are some exceptions maybe, like super high quality tannic young cabs maybe, that can "hang in there" an extra day or so. Air plugs may help too.
I finished a CDP that I opened on Tuesday, two days later. At that point, I just poured into a paper cup and had it with some pasta, just to finish it off. It was pretty gone by my standards, but drinkable. A cheap wine will be pretty awful after just one day or day of . The wine quality really has a lot to do with it. What are you opening?
My wife enjoys wine too and we have company often, so 90% of the time, we finish the bottle, unless it's a cheapie and then I don't care and use it for cooking for a few days.
I have stored good Ports in the fridge for up to a week though.