I have been playing a lot with cup shapes and sizes, and I have started to note a pattern with times of year, broken down by type of tea.
I have several different shaped teacups for Japanese tea, in two main categories. These being:
Wan - a cup that is a bit more a kin to a small bowl, or a smaller cup of similar shape to certain Chawans.
Yunomi - the what I like to call more traditional shaped Japanese teacup typically holding 6 to 9 ounces in a tall cylindrical shape. Such as the White cup pictured at the top.
But the general trend works in the fashion that the hotter it is outside the smaller the cup I want, with the largest surface area possible exposed to the air. I have often resorted to using multiple cups for myself in one sencha session in this fashion.
When the temperature outside is neither hot nor cold usually falling in the temperature range of 50-75 degrees outside, I resort to standard shaped wans. These seem to offer a bit of a stepping stone with a larger exposed surface area, but a larger volume also. But the fact that the temperature is in the in between stage they cool off at about the right rate.
Yunomi are my go to winter cups, simply because they in my mind act a bit like a chimney. All the water is stacked right on top of each other, and especially when made thick enough to have less heat loss through the sides of the cup, all the heat from the water on the bottom gets directed up to the water above it, therefore basically heating itself, as the surface area exposed to the outside is minimal but it has a relatively large volume.
For the longest time with Chinese teas I always used very small cups, where I might make the slight change of using a 1 oz cup instead of a half ounce in the winter. But now I realized I want my tea to be warm for a longer amount of time, and I can deal with giving it a little while longer to cool. As when using those small cups the last cup was always cold, unless I would drink the last three cups back to back to back in less than a minute, as while the fair cup keeps a significant amount of tea warm for awhile, when the fair cup has half an ounce there is no real heat retention.
So now I am exploring the option of using larger cups for basically a whole steep of Chinese tea at a time, and I have been meeting seriously mixed results. It almost seems like mediocre teas tend to taste best in larger cups, while the better quality teas should be kept to smaller cups.