My current batch size is 3.67 end of boil gallons, which yields about 3.33 primary gallons and 3 finished gallons. I built an entire brew house and kegging setup around this batch size. I even built a custom kettle that has the proper geometry for this batch size. I found that 3 finished gallons is big enough to share, but small enough to allow me to brew on a regular basis.
Agreed. I think I like to brew more than I like to drink. I only have about 5 beers a week. By brewing 1-case batches I get to brew once or twice a month without amassing a stockpile of beer that I'll never finish drinking. I have enough for my own consumption, some extra to share, and every 3 or 4 batches is something that I can cellar for extended aging.