Many districts use block scheduling.
The vast majority of school districts use a 7 or 8 period day. From an education journal published by the National Association of Scholars, the top 30 colleges in the country have an average length class period of 53 minutes. These colleges have the best students in the country who are most likely able to handle long periods of time. Hatboro Horsham is getting a lot of ink in the media. Their principal has been on Good Morning America.