Walter Murch has a rule about how much you can practically reduce the running time of a first assembly. This reduction is a little like reducing a patient’s weight. You can slim them down with diet and exercise and a lot of hard work, but there are limits.

Murch’s limit is a 30% reduction. If you have a 3 hour 20 minute film, you can reduce the running time down to 2 hours 20 minutes by trimming scenes, finessing edits: taking what you have and making it play more efficiently. If the distributor requires a running time of less than 2 hours, more drastic actions are needed. Plotlines need to be taken out, entire characters removed.

So be aware that a 120 page script may sometimes expand to a 160 minute film, but cutting the movie down to less than 115 minutes will require serious surgery. That’s why you’ll discover that your story will survive with a single kidney or lung, or even eye…