Someday I will scale down to smaller batches, but I have been on a lager kick for a few years now - making 10 gallon batches that meet their demise pretty quickly by friends and family, who occasionally drop off a sack of grain or some yeast or other ingredients to offset my costs a bit.
My ales are often 5 gallon batches, so if the lager crowd doesn't drink it, I have less to gift away or consume. I have a few folks that I brew for on a semi annual basis that like beers that I don't typically brew for myself, so that keeps me busy with requests for a case or two of a special brew for them, but usually five gallons and bottling half off the keg/drinking the rest from the keg.
A couple weeks ago a friend and I made a fifteen gallon 2 Hearted clone for an April wedding he will be attending. I have 2 weddings and a neighbor's graduation party to brew for next year (pretty early requests, admittedly). I enjoy the process, so for me there is no better way to spend a weekend morning. Smaller batches would be done more quickly, so if I were rushed, I could see the smaller batch size from that perspective. I get no greater enjoyment than having a first timer to homebrew declare that he or she just had the best beer that they have ever tasted (whether they mean it or not)....