Does add more learning time improve learning outcomes?

When I worked for education project at the first time, I remembered purchasing Edward D Bono book Lateral Thinking. There is famous question on the book as simile to the way human thinks: What will you do, if your well get dried? Maybe 95% of us will answer dig deeper in the same well. According to Bono, it is called vertical thinking. In mathematical term it is called linearity, and most organization tend to use linear approach such as more or double budget will improve the outputs and outcomes. How about learning?

Figure above shows Instructional time (bar, left) at school, and PISA reading score (line, right). Based on figure there is no pattern at all when we add more learning hours. We expect linear correlation would happen but apparently it was not. Patrinos simply make short quote to comment about reality described by figure above that additional learning hours will not improve learning outcomes automatically; the issue is not on incremental number of hours to improve learning but optimizing available time with relevant and contextual learning instructional design. Even you add more hours without improving learning strategy, the addition even contributes to student’s stress and depression.

Back to De Bono lateral thinking, our education system tends to use and gain vertical thinking. Just recently in 21st century, educators around the world make serious efforts to include lateral thinking (somewhat they call soft skills) into formal education system. Therefore, additional learning hours may be not important but enriching (widening) learning strategies are more important. This advice is supported by the fact that each child have different capacities and talents, multiple learning strategies will help child diversity to optimize their capacities and talents.