Alis has a recent post where she talks about walking and thinking about theme, and layering, and fabric--all the big issues. She calls this "helicoptering" over the book. But then she bemoans the narrowing of vision that comes when one arrives back at the keyboard.
I too love walking to think about writing, and it's nice to get the big picture. But I don't come home and sit down until I've narrowed back in on the scene I need to write. It's good to see the forest, but to write I have to get back down to the trees, and then to the leaves, and then to the pumping osmotic pressure in the veins in the leaves, and I don't sit at the keyboard until the big picture has been replaced by the twitchy obsession to write a particular bit.
I don't even try to remember why I'm writing the scene--I just remember the general idea and the atmosphere and effect I'm striving for. I don't try to remember the big picture while I'm writing. I just trust that it made sense while I was out walking, and that now I have to sit down and do the little task at hand...and pray that my subconscious, instead of wandering out into the yard and snapping at flying insects, hangs around to furnish me with the thematic underpinnings, symbols, subtext, and all that jazz.
I'm sure some people can be deep into a scene and also be consciously aware of all the subtle interconnections of the elements of the scene with all the levels of the book as a whole. There are also people who can tap dance while playing a musical instrument and simultaneously juggling plates. More power to them, but I am not in the ranks of either of those groups.
When I'm writing, I am deep down in my burrow, working in the dark in a very small space on some tiny little problem, and I fear to pop my head up into the sunshine because I'm certain some predator's claws or jaws are waiting for me. For me, while at the keyboard, the big picture is sure death.
So I walk to look at the big picture, but zoom in before I get back to my desk. The only problem comes when I can't zoom in on the scene that needs to happen next. This can result in what Pooh would call Some Very Long Walks.
You know those people who walk or jog across continents, or around the world? I'd guess some of them are novelists who can't pin down the next scene.
Of course, lately I can't do the big picture or the small. So I haven't been walking.
I've done some whacking at plants with garden shears, though. I think of it as editing the botany in our yard.