When I take the time to actually think about it. I often wonder if I should replace "it" with something more exact. eg.
When I take the time to actually think about the appropriate use of the word "it".
I know what I'm referring to by the "it" and I don't usually consider that others might not know. But then if I replace every instance of the use, it can make reading feel overly verbose and redundant.
I'm not a language major, so I rely on my "feelings", for what they're worth. If it feels "clunky" I rewrite the copy.