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In regards to keyword targeting the first goal is to write in a way that is natural for the end user. You shouldn't focus too much on trying to include your core keyword a specific number of times there isn't a hard and fast rule for that. What I would look at instead is keyword density. This will take into account your longer form articles. But you shouldn't focus too much on hitting certain keyword targets but focus more on producing great content that solves a particular pain point. Hope that helps some.