Plan to Percolate
I often spend an hour pre-thinking about a topic before I "need to," not because I'm pressed for time, or because it's new material, but solely to allow me to percolate. Planning to percolate is a good use of your brain.
If you don't know what I mean by "percolate," it won't help to look it up in the dictionary. It's a technical term, whose first definition is "to cause (a liquid) to pass through a porous body." I didn't originate the mental meaning I'm ascribing to it, but it hasn't made it into the dictionary yet.
It means thinking about an issue in depth, then leaving it in the background for a while, to let additional ideas burble up from your subconscious. You come back later to think about it in depth again, with the benefit of the additional ideas.
The first period of thinking activates relevant information in your knowledge bank. Then, as you go about your business, chance observations and incidents will trigger additional information and new connections on the topic. When you come back to the topic, you have new insights and identifications to help you.
I believe this use of "percolate" comes from having heard coffee percolating in the old days. In the old way of making coffee, pressure built up to force water over the coffee grounds once every second or so. Each time this happened, the coffee made a burping noise. It's the perfect sound-effect for a new idea burbling up from the subconscious from time to time.
But back to the subject: planning to percolate is a good use of your time. Here are four reasons:
1) A few hours is about the limit of a typical person's ability to concentrate, so you can't expect to think through every aspect of a complicated issue in one sitting. You might as well plan to have two sittings, and take advantage of making extra connections in-between.
2) It can be difficult to heat up your mental circuits on a new subject all at once. It is easier to warm them up with some pre-thinking, then keep them warm in the background by percolating. The new ideas that come up while you're percolating motivate you, making you eager to go back to the subject for the next round of concentrated thinking.
3) The total amount of thinking time is less. The extra ideas you get while percolating are "free" — they don't take concentrated thinking time.
4) When you have time to percolate, you are more likely to get some creative ideas, particularly in answer to any interesting puzzles that come up in the first period of thinking.
The next time you are starting a challenging project, plan to percolate. Warm up your own mental circuits in advance, and look forward to making the whole project move forward faster and easier.