Revising is as individual as writing. There's no wrong way to do it, and there are no hard and fast rules about how it goes.
There are very few arts or crafts where an important part of creation is destroying part of what you've created. Even sculptors don't have to make the marble before they start chipping it away.
Over time, as you write more, you will learn to recognize which ideas can be developed easily, which can be developed painstakingly, and which can't be developed. And you will learn more about your own process of development, which will help make both easy and difficult development go more smoothly.