To read in and out genre, all lit.
To put finished work aside,
Let it breathe, find its own stride.
The gap shows you what needs an edit.
I find reading non-fiction helps widen my mind and would read it in any case but I’ve found that finding out how something happened in the past could have a direct bearing on how I invent my fictional worlds. I love British history in particular and the tensions within it I have used to help flesh out the political side to how the Queen governs and how she handles L’Evallier especially (she’s loosely based on Elizabeth 1st and he’s her equivalent of Burghley but I needed to know who to use as a model).
The way to really write well
Is to ignore all the hell
Of edits and rewrites
They help make the work right
Remember to show, not tell!
I think it best to assume you never write anything perfectly first go. There’s little that can’t be improved with a second or third or fourth read through. You will pick things up you missed as you wrote the work. Also as you read through again and again, is the story still gripping you? If so, good! It’s got life in it. If you’re not gripped you may have a problem. You will come to a point when you genuinely feel you can’t edit it any more. That’s the point to send the work out and test the market with it, but the story itself you should still care about deeply.