People say I pay too much attention to the look of a movie but for God's sake, I'm not producing a Radio 4 Play for Today, I'm making a movie that people are going to look at.
Same thing with film, by the time you've finished shooting and you've really been into everything, you've touched up everything in the editing room. You've gone in there and taken little bits from everything.
What you do, is you gradually become more and more experienced, and more and more realistic about dramatic tolerance, i.e. about how long the play should be.