I think what you’re referring to was said in an online discussion group.
A second really common bit of advice for any creative person is to have an ‘Ideas Diary’. This can be as simple as a tiny spiral notebook that fits in your pocket or backpack or can sit by your bedside or your computer. Most likely you’ll find that you ‘hatch’ great story ideas at the oddest moments; just before sleep hits you is fairly common.
And one of the other most common occurrences is just as you are sitting down to really tackle a tough piece of writing. Human beings are escape artists at heart! It takes discipline to put yourself in front of the computer every day that you’re scheduled to write and ‘make’ it happen on the page. Far easier to simply play the story (any story) in your head, scrolling through the action but never really writing it down. It is this discipline that makes writing hard. Everyone has great movie ideas but very few people take the time to acquire the discipline to transform those ideas onto the page.
And that’s where the LIST comes into play. Often, fantastic story ideas come out of that desire NOT to be nailed down to a schedule. USE THAT; in fact learn to use all the tricks your mind will play on you to your advantage. Do take five minutes (not five hours) recording this NEW , great idea in your story diary. But DON’T GET SIDE-TRACKED from your current goal; FINISHING YOUR FIRST DRAFT.
Remember, that is the only one rule in beginning that first draft screenplay; FINISH IT. Everything else is probably fixable in a rewrite. But you really can’t fix, what isn’t on the page. So record all the new story ideas that will come your way, while you’re acquiring the discipline to finish that first great story idea that got you started!
I hope that helps. And I wish you luck with your screenplay. Let me know when you’ve completed your script. I’d love to read your work!