Part of my common sense approach arises from my professional background. This includes illustration as well. Sometimes I was allowed to work freely on splendid and phantastic illustrations, but most of the time I was just sketching so called 'scribbles' for the advertising business.
Scribbles are quickly drawn illustrations that never appear in the public. They serve to illustrate (literally) a situation that will later be one of these beautiful photographies we all know. Making scribbles brings you down to earth. Nobody wants art there. You have to be quick and ? most important ? the illustration has to remain 'general'. Both art director and photographer want to realise themselves and both do not want to discuss details with the client at that level.
This non-bonsai introduction is to show you, how I sometimes look at things and where part of my ideas come from. But now to the question of one or two windows: In fact I would never even have thought about two windows. Because of the years of scribbling that lay behind me. There you have a simple rule concerning 'outdoor-situations': light comes from one direction only. This is not because the sun shines from one point. When you go outside, you will find very complicated situations, light being reflected by bright walls or water surfaces. It could be 'natural' to have light from several sides. But when you scribble, it will hardly ever look good. Maybe this is because we KNOW the sun shines from one point only. Knowledge is a very strict censor to our comprehension sometimes. Too, we are not able to 'see' too much at a time. In a Tokonoma there is a tree, a little plant and a picture in the background. Three points ? another of my 'scribbler's rules' says: Three points are perfect. When I speak of 'points', this has a double meaning indeed: Either it can be a point in the sense of a location or a point in the sense of a 'value unit'. So a point can be a thing or an effect!.
Light in a Tokonoma is such an 'effect point', it is background, surrounding, but has a 'value'. But it should help the 'things' and not rival. So it must not be too complicated in itself. Looking at trees alone I find something similar: Some trees are unattractive, because every single design aspect has been styled up to the same importance. Thus moss, trunk, foliage, pot and jins speak to you at the same time in the same loudness like a bunch of kids reporting what went wrong. Right now, such a problem is being discussed ? the Dancing Crane's pot.
I like the idea of examinig the visual flow in a Tokonoma very much. Since I personally (or rather visually) always end up somewhere in the middle of the picture and do not search for an outlet (might be zen?), I started to think about other possible ways to understand the window.