Even though there are a lot of good rules when it comes to writing, some rules are more important than others. No matter how good you are as a writer, some of these rules are so important that you should almost never break them.
For example, when it comes me, I pretty much always try to obey the rule of 'finish what you start writing'. No matter what happens, I try to get the task done, so that I could feel better about myself and that I could move on to something else.
Still, even though this 'finish what you start writing' is a super important rule, it's not the most important rule about writing. Writing and managing to finish your screenplay is only the second most important part about writing.
At least in my opinion, the most important rule about writing has to do with 'publishing' and 'rewriting'. No matter how good you are as a scribe, you should never publish stuff without rewriting it - unless you absolutely have no other choice.
By that I mean that it's almost impossible to ever get everything right in your first draft. It's pretty much guaranteed that every single time you will make some fairly big mistakes that you won't be able to pick up right away.
When it comes to rewriting and getting things right, there are no quick fixes for it. It always takes time and you need to be able to clear your mind, get a fresh pair of eyes and more or less forget what you managed to write earlier.
Writing good stuff simply isn't about who's the fastest writer or who's the first to get certain amount of words on paper. It's not about rushing to the finish line and thinking that being fast makes you somehow special as a writer.
On the contrary, writing good stuff is always about being aware of your flaws and being aware of you making mistakes. It's about being aware of your weaknesses as a writer and knowing where you're likely going to go wrong.
Especially when it comes to me, I have too many times published scripts and articles without thinking them through enough. I have written them in a hurry and thought that there was no difference whether I gave them another look or not.
If only I had understood earlier that I didn't have to publish everything right away as a writer. If I had only understood that writing is so much more about rewriting than it's about being fast, things would have been so much better.
As a whole, even though it's obviously important that you almost always have to 'finish' your projects, that itself isn't all there is to writing. It's not the only thing that matters and counts when it comes to creating quality stuff.
On the contrary, being too content with having finished your first draft doesn't mean that your job is now done. It doesn't mean that you have figured everything out and that you can now start slacking with your project.
In reality, writing your first draft is only the first part in the writing process. It's only the first step, and in most cases you have to do a lot of rewrites before you can be certain and confident that your script is in good shape.
In that sense, there is absolutely no shame in not getting everything right the first time. There's no shame in admitting that you made a lot of mistakes in your first draft and that you still need more time to get things figured out.