The release is after the ball is struck. The vast majority of hitters release the top hand after contact. Some sooner than others. Leaving two hands on the bat after contact throughout the swing serves no useful purpose. In fact it can be detrimental to the hitter. Young hitters can have a tendency to release too early. They also can have a tendency to focus so hard on leaving two hands on the bat they actually limit their ability to have any extension in their swing. You can use Q's to help players stay on the ball longer by saying leave two hands on the bat understanding that at some point the top hand will release.
I challenge any of you to watch college or professional hitters "mature accomplished" hitters and watch what happens to the top hand after they have hit the baseball. Stand up and take a swing with your hands with an imaginary bat in your hands. Drive through the baseball keeping your head still and extending through the ball. What happens to your top hand? What happens to your head and shoulders when you intentionally leave the top hand on? Now imaging a ball on the outer half with that swing?