One stops worrying about bottle boundaries. One buys magnums. ("A difficult size, too much for one but not enough for two.") There is a faint mellowing effect by the next day, but nothing like the effect of oxygen.
We sometimes deliberately skip argon. In Italy you know you're tight when friends serve yesterday's wine. Those wines need the abuse. Most wines don't handle the abuse of an open day well.
Scale matters. There are $300 units made of cheap plastic aimed at wine "connoisseurs". The cartridge is the same size I'd carry mountain biking, to fill one inner tube on an emergency basis. That's supposed to last 50 bottles? How stupid does the manufacturer think I am?
Yes, argon is heavier than air, but there's this thing called diffusion. There's argon in the air around us; if argon cleanly separated from air and formed a bottom layer, we'd all suffocate when we lay on the floor. Obviously, we don't. Put it together.
I'm reminded of Thomas Keller's Bouchon Bakery cookbook taking heat for proposing 350 ml of water for bread steam, poured onto 30 lbs of thermal mass such as an aluminum disk in a cake pan. That also generates enough steam to displace the volume of an oven threefold. A commercial bread oven depends on serious steam for the first few minutes; this is a home approximation. People liked the idea of spritzing 10 ml of water from a plant spritzer, and were offended Keller did the science. They were just genuflecting.
One can wait months to obtain medical grade argon. It's the same process, only tested to confirm the fact that the process doesn't introduce toxins.
My wife is a practical engineer; she indulges every exploration like this. Some take. This one took. A standard after-dinner question is "Did you argon the wine?"