All together at designated times of the day.

... In a big group at certain times of the day. There's a separate room from the normal bathrooms in which people all get together and pee in a big group, similar to how your world eats meals. Poop is still handled like it is in your world, but if you pee in the toilet you might be judged for your weak stream later.

A side effect of this communal pissing is that people tend to be much more liberal about their body, having seen genitalia 3 times a day for their entire lives, and gender segregated bathrooms aren't a thing there. Also, meal times are much more rigidly adhered to."