Henry Poincare seemed to work this way as well (source):
An interesting aspect of Poincaré′s work is that he tended to develop his results from first principles. For many mathematicians there is a building process with more and more being built on top of the previous work. This was not the way that Poincaré worked and not only his research, but also his lectures and books, were all developed carefully from basics. Perhaps most remarkable of all is the description by Toulouse in [30] of how Poincaré went about writing a paper. Poincaré:-
… does not make an overall plan when he writes a paper. He will normally start without knowing where it will end. … Starting is usually easy. Then the work seems to lead him on without him making a willful effort. At that stage it is difficult to distract him. When he searches, he often writes a formula automatically to awaken some association of ideas. If beginning is painful, Poincaré does not persist but abandons the work.
Poincare also expected the unconscious to keep working on the problem after “he” had stopped:
Toulouse then goes on to describe how Poincaré expected the crucial ideas to come to him when he stopped concentrating on the problem:-
Poincaré proceeds by sudden blows, taking up and abandoning a subject. During intervals he assumes … that his unconscious continues the work of reflection.
Henry Poincare seemed to work this way as well (source):
Poincare also expected the unconscious to keep working on the problem after “he” had stopped: