I like to work like this as well. Which is why a lot of technical tests seem quite nonsense. For complex problems I have stuff running in the background of my head for a day or two, weighing up the advantages and disadvantages of the various options. The best solution usually becomes apparent at some random time, like when I am cooking dinner, not concentrating on it for 5 minutes after first seeing the problem. And as you say there is usually plenty of other work that needs done in the meantime.