Yes, especially when you need a tight word count. Otherwise you end up writing a whole lot of words to get where you need to be for the story then have to remove them afterwards. And that is painful sometimes when the words were good but you need to tighten. It still happens sometimes that we need some meandering to get things fleshed out then tighten after, but it really can help to have a rough guide, even when you accept characters don't always do wht you want them to.