I misunderstood, apologies. Agree that vacuvin’s aren’t worth much. Cooling (refrigerator) slows the rate of any reactions, which is the main thing, imo. I used to wonder about exposure to oxygen during the pouring off into 375’s, but my experience is that, if done expeditiously, the ensuing oxidation is substantially less than leaving the wine in a half-empty 750 for 18 hours or so.
Ime, pouring into a 375, if you do it right when the original 750 is first opened, has an affect over several days similar to that of slow-oxygenating a large bottle - a la Audouze - over, say, the length of a day. So we take this measure when we don’t think we’ll get back to the second half for a couple or three days. It’s a practical technique if you want to drink through a glass each of two or three wines at dinner with a significant other.