Well, I certainly make less than the legal limit... that is a ton to me. I share a decent amount with friends to get feedback on what I have made.
In the case of the wine kits when I make a pyment, I will typically get 2 to 3 times the volume as if it was made as a straight wine. Those typically will go into an oak barrel and site for a year as they need aging just like a typical wine does. Those barrels will lose volume as part of being in a barrel, then I get to minus the tasting that get taken... sometimes that equals a lot over the year.
You ever wish you had mead a year or two or more down the road to see how it ages and matures? That's difficult if you drink and share most of it. In short, you have to make more than you drink and share. My pyments are an example of ones that get set aside with a variety drank short, medium and the rest set to see how they are a few years later.
Some meads like the sessions and some fruits ones are ready for consumption in relatively short time and those get enjoyed close to immediately. My Blueberry Cyser is one that just can't hang around long enough.
I used to mostly make 1 gallon batches and advocate that approach while learning and practicing, as well as recipe development.
The second mead I made (1 gallon) was just too hot and not very tasty. I periodically tasted it and it just sucked. I eventually stuck it to the back and forgot about it. About 16 months later while bottling 1 gallon carboys I found it. I tried it again and it was spectacular and I only had about .6 gallons left. I had waited so long and it became great, but I had so little. After that is when I started to make 5 gallon my standard size. If I'm going to wait them out, I want to make that wait more worthwhile.
I have a variety that are still sitting around in carboys because I really do not enjoy bottling. I guess I'm a bit of a pack rat with the mead making. Those that I really enjoy don't seem to hang around as long as I would like.
A bit long winded answer, but I think that tells you what you asked.