The big, round ice cube tray was a gift from a member of a country club where I used to tend bar. He used to bring his own, personal thermos full of round ice cubes to cocktail hour for his Chivas on the rocks. He specified that we put only one, single, round ice cube in a rocks glass and pour the Chivas over it. Once, I asked him about it, and he explained that it was a superior design. The larger, denser ice cube melted slower; therefore, not watering down his drink as badly. Also, the single, round cube made it easier to drink. He went on to say that fancy bars in Japan and China would use some kind of device to apply heat and pressure to similar round cubes, and that doing so would make them perfectly round, seamless, and crystal clear. So clear, that when added to a drink, it looked as if there was no ice at all!
Iced Sencha over big, round Sencha ice cubes. Smart.