Teenagers and adults produce about 1200-1700 mls of urine per day. The more you drink, the more urine you produce. Children produce slightly less urine. Most people empty their bladders 4-7 times per day, mostly during the day, seldom at night. You normally pee about 200-300 mls at a time. If you empty your bladder by CIC, you should empty it about every four hours during daytime.
Small children completely lack the ability to control their bladders. They urinate into their diapers about once an hour. During their first years, they slowly but surely learn to control their bladder. By the time they start school, most children can "hold their water" if they have to and can also pee on demand.
But by school age, one child in ten actually still has an immature bladder which he/she cannot control, no matter how much they want to. Their bladders still need a year or more to mature. So yes, they do "grow out of" this problem.