Some people mow twice a week. Lawn is basically their hobby.

Much, much less. The city I live in wants to promote biodiversity and has adapted their mowing schedule for this. Large parts of public greenery are only mowed once or twice per year. Other parts 6 times a year. Some parts are mowed 20 times a year, e.g. fields for kids to play on, or where it would be a safety issue (e.g. high growth blocking view around a corner), but that’s just a small portion.

Also in some parts they only partially mow, to create spaces where there are different heights of greenery. They also sowed a lot of mixed flowers, which looks really nice.

I usually have to mow once a week when we're not in drought, otherwise the lawn gets too high, but during the heat of summer I don't have to mow at all because the grass goes dormant.

Before I bought a house, I only knew once a week when I was growing up. Seemed to be based on the neighborhood (upper Midwest).