AKA "back burner" AKA "sleep on it". I've grown more and more to appreciate and try to use this modus of thought as much as possible. For me, it's cycles of active research and "cramming" everything I think is relevant to a solution into my mind, then a complete release of the stress of an active search away while I do something else and let thoughts of my previous problem come and go as they please. Sometimes, creative solutions come in the form of a self conversation in "language", other times it's sort of non-verbal, like visually seeing the problem from different perspectives. For me, this happens in the gym, while cleaning, doing dishes or other chores, while driving, etc. It takes practice but it's a very interesting thing to experience. I feel like sometimes it's the release of focus that lets the network of systems in your brain accept new stimuli from other systems and senses and tickle the thought in new ways.