I use spare time (time not on the honey do list) or sleepless night time working on problems (I then re-think them in the morning when I am fully awake to see if they even make sense

and some of them do). Come up with an idea, then look at it in a 360° view rather than a tunnel view for the faults or improvements in other spare time periods.
I just started rearranging and cleaning up my garage this week while looking at my buggy for many other things as a wide look can find things that affect the narrower scope of problems being worked on at the time (it does make sense). Over 10 years ago I built a 66" long table and I finally got it moved to where I built if for opening up that one end of the garage for more junk

. Other than the physical part of moving things around it doesn't take much time and the change is to the positive giving me that small bit of more thinking time. Garage time is precious even when one is retired so time in there, even if it isn't much, each day is a good idea; it also keeps you connected to the project rather than turning into a task. Also, you never know when a quick side causes you to see/notice something that is going to lead to something positive.
Keep up the good work as it looks like you have a good handle on what you are working on.
Lee