Even when drinking alone, there are often rituals. It's the same in spirit for everyone, but the specifics are individual. For me it plays a lot like in a certain song: waiting for the water to heat up without boiling, thinking about life, often watching the sunrise or recalling some dream.
Perhaps that's why the Druze would stick with the custom, too. I think that they "get" it - it isn't just "drinking", it's also the introspection that comes with it.
There are also plenty local differences. For example, the grandpa in the pic has a coconut-shaped gourd, fairly common there in Uruguay; here in Paraná (1000~1500km up north), in Santa Catarina and in Rio Grande, gourds typically have a large lip, like mine:
The ones that I saw the most in Argentina are from a third style, kind of a middle ground between my gourd and that grandpa's gourd.Then to the West (Paraguay, Mato Grosso do Sul, and even a chunk of Paraná) you'll often see people using cow horns for tereré.
What you drink might also change depending on the place. Even among hot mate drinkers; for example the further south you go, the more roasted is the yerba. It can be also coarse or almost like a flour in texture.
And a heartfelt hi from another A Clockwork Orange fan. I bloody love the book. (And the movie, too.)
Truth is, I was trying to be simple, so I mentioned the horns/guampas in MS instead. It seems to me that they (you?) consume mate far more as tereré than hot mate/chimarrão. Even some of the folks in Paraná's third plateau would rather use glasses. (I'm from Curitiba, so rather far from them. The first time I saw it - mate on a large glass, with lemon soda - I couldn't help but "...what?" It's comfy in the summer though.)
I just know from a friend from out there that it's common to use both the horns and the gourds. Mate with lemon soda is something new to me. Mate tea with lime served cold is a refreshing drink I like, but then it's made with the toasted leaves and not just dried like chimarrão.