Our only choice is to follow the tangents as we write. The possibility is good that we will never use them. Our story can go in a completely different direction. But we have to follow them either way.
An outline is supposed to remedy this, but even then you can create outlines that are vastly different than the final draft. Outlines are different more than they are not.
The only way to know your story is to tell it. And until you get to the final version, you must tell it in all its forms.