This is something I’ve learned to do during NaNoWriMo years ago, and that is that I just NEED to write every idea that pops in my head, no matter how far away it seems for my story.
I toss these tangents in a folder called Scenes for Somewhere and they are always crucial. Sometimes they fit in somewhere in the book, sometimes they spark a whole new story.
There are so many people who advice you to stick to your story etc, but sticking to your tangents is important as well.
One year during NaNoWriMo, I had NO idea what to write for the book.
I dove into Scenes for Somewhere and found exactly what I needed and it only needed minimal rewrites.
This is also one of the reasons why I sometimes write out of sequence, because one scene further on in the book wants to be written and that makes it so much easier to write the chapters in between.
I use the same method for writing short stories and blog posts. It’s what works for my mind so who am I to try and change that?