Every profession/business has “rules of engagement”. And, every profession has those people who can and do successfully skirt them. Sorry to say it is not the majority of would be writers out there.
As has been stated by many, “writing rules”; such as type face, spacing, black space vs white etc, are more like conventions. That said, unless you are an established wordsmith with the chops to flaunt these conventions, AND enter the script pipeline high up the approval chain, you’d best take the “rules” to heart. Why, you ask… don’t; just do and try not to get confused with the why. Just know there are good reasons for them.
Write from passion and commitment and compel the entry level reader, the one most likely to be reading your script, to turn the page. To keep their job the reader’s easiest answer is NO. Your only job is to entice them to say yes and help them keep their job. They all want to be the one who “discovers” the next franchise tent-pole blockbuster.
Remember, just ’cause you like to drive on the right side of the road is no reason to insist on it, especially in the UK.
What a competent consultant, instructor, adviser, guide or mentor will do is attempt to prevent a novice writer from shooting themselves in their typing hand before the first script page is turned. I have seen scripts trashed because the writer had oversize fonts, a WGA reg number, and a copyright symbol on the title page. Reason … signs of an amateur. The reader’s comment “I might read it when I get through with these” indicating the two dozen or more scripts pilled on her desk. It never got read.
So, it’s your decision, rules or not. DO NOT cite a produced script as your model. Instead try to find the spec script of a sold and preferably produced screenplay. Trust me they are almost like hen’s teeth.
Don’t let any of what’s been said here rob you of your vision. You can learn the game as you progress. Above all, write. Just don’t submit until someone who keeps up with the ever changing ropes spends some time with your masterpiece.
Remember, your script is your calling card and resume rolled into one. (^_*)