Concerta only lasted about 8 hours with my son. His doc told us that the effects are different with everyone and that some kids actually need 2 doses in the course of a day!
I just started on Concerta 18 mg and I take one a day, first thing in the morning. So far, mine have lasted all day. I'm on one a day until we see how it works. Before meds I had problems sleeping so they didn't want to me take one close to bedtime. So far so good. But I must admit, it's only been 3 days.