Teapot size

I haven't been able to get my head unwrapped from this problem. I've heard from several different people that large yixing teapots used for a gongfu type brewing result in tea that's subpar. I'm not completely sure why that is though; the most immediate answer is something to do with the temperature, in that small pots hold in the heat better than bigger, roomier pots. But I'm just not convinced. I've learned about this in Biology and I've done the math. Objects with a large surface to volume ratio lose heat quicker than objects with a smaller surface area to volume ratio. Take for instance my little yixing pot which is 180 ml/cc. V=.75pi*r^3 and Surface area=4pi*r^2. For the sake of simplicity, and the fact that I have no clue what kind of equation would give me a graph of my teapot's shape, I'm assuming the teapots are spherical. With this I get a ratio of 5:6 (or 5/6). But if I use a teapot that is considered to be a good size, 120 ml, I get a ratio that's approximately 1. All that really means is that the surface area is the same amount as the volume, but it will lose heat faster because it's has more surface exposed compared to its volume. This ratio and reasoning also explains why small animals have high metabolisms. But I'm not completely sure how this could be a benefit to teapots. For right now I'm going with the two-fold assumption that: yixing teapots are traditionally small which allows for large leaf to water ratios producing better brews of tea, and the small size was originally intended for the use of one teapot per person.