FWIW, I'm a wine drinker a wine hobbyist for about 25 yrs. I'm no expert, however. I may ramble and prattle and maybe repeat things said before so pls forgive me if I do.
I judge shelf life by my tastebuds. A well-sealed but previously opened white wine can taste acceptable to good after about 3-5 days in a refrigerator which keeps 40-45 deg temp. Sparkling wines, blush and rosé I keep in frig. Most red wine I keep out of frig but away from light or heat for up to a week. After that time (more than a week) I taste it, but most likely I'll put it in a red sauce or toss it.
Typically to make a red last a full week, I use a very good sealing cork. I haven't gone to a vacu-vin system or anything exotic. However, after a week it tastes off to my taste buds... a bit puckery...vinegary or oxidized.
White wines (that I buy with my limited budget) are often less complex and as such I only give them 3 days. I mix them into salad dressing or make a white sauce with them.
Unopened wine is a whole other story. Quality red wine (that is worth aging and maturing) can last 10-15 yrs or more. In fact, with the 'sophisitcated' wines it is suggested to age in wine cellar conditions. Typically, and on average, red wine that is not expensive (under $15) isn't worth aging or keeping in a wine rack for more than a couple years (up to 5) under good conditions.
Typically very few (but a small minority) of white wines can have a long shelf life unopened but are predominantly not in the affordable range of under $15.