6 looks line a nice binsize for age: roughly 0-6 are infants, 6-12 are prepubescent kids, 12-18 are adolescents, 18-24 are university age, 24-32 are young adults, which is IMHO some nice detail. Also, 32-48 early middle aged, 48-64 older and 64+ elderly; but after "university age" and maybe "young adults", categories are a bit more cloudy.

The graph below is using data from https://code.datasciencedojo.com/datasciencedojo/tutorials/raw/master/Introduction%20to%20Data%20Visualization%20with%20R%20and%20ggplot2/titanic.csv See how esp. bars 3 and 4 are affected.