Annie Dillard said this quote

One of the few things I know about writing is this:spend it all, shoot it, play it, lose it, right away, every time. Do not hoard what seems good for a later place in the book, or for another book; give it, give it all, give it now. The impulse to save something good for a better place later is a signal to spend it now. Something more will arise later, something better. These things fill from behind, from beneath, like well water.