This latest ASCD SmartBrief post says it all!
Richard

Report: Extra Educational Time Didn't Help Struggling Miami Schools

"A three-year, $100 million plan that sought to improve student achievement at 39 struggling Miami-area schools through the implementation of a longer school day, a longer school year and an intensive reading program had very little effect on student test scores, according to a district report. Instead, students as well as teachers were worn out by the extra time and work, the report found, and students in the targeted schools actually scored worse on writing, math and science state tests than peers in schools without the program." The Miami Herald (5/15)
http://www.miamiherald.com/457/story/1049341.html