How much planning do you do before you start to shoot a scene?
As much as there are hours in the day, and days in the week. I think about a film almost continuously. I try to visualize it and I try to work out every conceivable variation of ideas which might exist with respect to the various scenes, but I have found that when you finally come down to the day the scene is going to be shot and you arrive on the location with the actors, having had the experience of already seeing some scenes shot, somehow it’s always different. You find out that you have not really explored the scene to its fullest extent. You may have been thinking about it incorrectly, or you may simply not have discovered one of the variations which now in context with everything else that you have shot is simply better than anything you had previously thought of. The reality of the final moment, just before shooting, is so powerful that all previous analysis must yield before the impressions you receive under these circumstances, and unless you use this feedback to your positive advantage, unless you adjust to it, adapt to it and accept the sometimes terrifying weaknesses it can expose, you can never realize the most out of your film.

Stanley Kubrick
July 26, 1928 — March 7, 1999