There are many kinds of stories just like there are different kinds of animals. And they have their own anatomy. A structure. Although sometimes the structure itself may be hidden, as it is in stories worth reading. That is a personal opinion. I am fond of the strange story which goes all over the place and then takes you to the end. I am not talking about thriller or suspense works.
I do not mean the kind of aimless meandering that comes of not not having and end in sight. Many authors even great ones have trouble ending a story than beginning it.
A phrase, a sight or a smell could start a story. But how do you end it. An earthworm has a beginning and an end. But where does the body of human beings end. At the feet or the hip. I have no question about the head you see.
This is why some gentlefolk recommend an outline. You work your way from the head to the tail if you have one. Your head is fine in shape and structure. Maybe even the middle is ok. But the tail. See how it tapers after the vestigial hind limbs.
A happens. Then B and finally C. But maybe you cannot quite understand the C because it keeps wriggling. Life is a serpent. And a story is about life. Even if at times the life is Strange.
So planning is good for the story. Yes. You know the route. But at times I think it is better to just walk, with no aim. Go where the characters take you. They are alive. They want to live their own way. Same as people.
They will take you to the end. Then you have to find the Middle, the path they took to reach the end.
I read a feature on the five act story writing a couple of days ago. It left me aghast. Did Shakespeare know about the five act or even the three act model. He wrote. And his stories still stand not because he planned them that way, I am sure.
Great art just sprouts like a great flowers. But it certainly needs fertiliser and water.