I’m not quite sure who said this, but I saw this somewhere. She basically said that no one can write and edit at the same time. Allow me to paraphrase.
Write first; edit later.
The logic behind that is if we are so caught up in if we have the right tense of the word, or the right spelling of the word, or anything like that, we very often tend to lose our train of thought and can’t write much of anything. So don’t correct things that can be corrected when you edit. Don’t even think about it.
I oftentimes will write something and realize I placed the word “was” in my sentence. Now, if you know me, you know I hate the word “was.” However, I let it stay, because oftentimes if I try to write my sentence without was in it, I lose everything I intended to say later on. So keep this in mind, no matter what you’re writing.