I have found that dominating long tail keywords helps me take a stronger position on short tail keywords that are similar. Not only is this a quick win and drives more qualified traffic through long tail, the LSI kw approach can be impacted from the footprint. Not sure if that is 100% for anyone else, but in several niches I took this approach and it helped.
Think about the keywords that will drive more qualified traffic IMO. If your keywords are saturated, then you will have lower ROI. Hope that helps.