Focus Mode vs. Diffuse Mode
Focus mode is a highly attentive state and diffuse mode is a resting state where the brain is actively working on something in the background without actually focusing on it. The diffuse mode, letting the mind wander, can allow different areas of the brain to hook up and return valuable insights. Focus mode is required and an important element of first learning the material, but being in focused mode too long can detract from learning. Focusing on the problem for too long may result in tunnel vision and the loss of the ability to think outside-the-box to solve a problem. This is known as the Einstellung effect. When stuck on a problem, take a little break, let the mind go into diffuse mode and then start with a clean slate in focused mode.
Alternating between focused and diffuse thinking is the best way to master a subject or solve a difficult problem. First, we use the focused mode of thinking to understand the basics of a topic without any distractions. Then we use the diffuse mode to passively internalize what we have learned and make connections to other things we already knew. Afterwards, we go back into focused mode and pare down the connections that we made to the best, most helpful ones. (Examined Existence, 2015)
Stopping work for 10 minutes while you read a funny story or play a game online can give your brain enough respite to switch into diffuse mode and start churning away. (Parker, 2015)
One technique that help switch between modes is the Pomodoro Technique.