What Are Margin Notes?
They're notes made in the margin of a document...
In all honestly, margin notes are important when developing your script into something stronger. They are broken down reviews of each scene. It studies the structure, sequence, dialogue, tone and setting of that scene to make sure it moves the plot forward. It should also be short and to the point and will usually point out some flaw in your script.
Have no fear, it will open you mind to another way of getting the scene to the point it needs to make. It also helps to point out things you as the writer do not notice.
They are a great source of information.
One thing you should not do, is send a questionnaire when you have asked a friend to read your script. What you are looking for is the first impression when it's read, not thought up answer based on a test like sheet of paper that brings up horrible exam memories and nightmares of going to school naked.
Just don't do it.
Either the reader thinks that there is a right and wrong answer, or they don't want to spend the time to re think or re read a certain part in the script.
This is why margin notes are one of the ways to go, you get that initial response and feel right there on the margin.