Draft one of a manuscript is for you. In this draft, you get to tell your story to yourself. You can write as much as you want, go off on tangents or side quests, or infodump and worldbuild to your heart’s content.
There are many ways to approach manuscript editing, each with its own particular process, and nearly every editor and writing advice site has their or its own method. This post will describe the most common types, explain what they’re for, and provide questions you can ask yourself to ensure that you’re approaching this stage in the best way possible.