I have this theory when I teach writing, that it’s easier to learn things if you break them into separate techniques. One of the things a writer needs to learn is how to edit. It can be totally overwhelming, which is why you’ll hear the advice about “Turn off your Internal Editor” when writing.
I think that having an active internal editor can actually make writing faster and smoother but trying to train yourself to edit and write simultaneously is a bad plan. SO here is a lecture from my “Writing on the Fast Track” class about how being in a critique group can help you train your internal editor.