Spending some time doing R&R might set the creative juices flowing. Over-focusing on one single problem might lead to burnout and then anxiety and the feeling of being mediocre. Humans have a few basic needs, and excelling at work is just one of them, if we ignore the others we might sabotage even the one we care explicitly about. It is good to switch back and forth between work, learning and just being passive and enjoying your senses.