12 changes a day is not a huge outlier, but it is on the high end. Standard pediatrics holds that a newborn - infant that is not dehydrated should be producing 2-8 diapers of urine per day. A newborn should be producing a couple of BMs a day, down to once a day by age four (though IME once/day even relatively soon after birth is pretty common.)

And the articles does say “as many as 12, though older kids need fewer.” So, that seems spot-on.