Low Hanging Fruits (LHF)
Being associated with the SEO community, you can understand that by working on 5 keywords, leads to other potential keywords getting affected. The only way you can perhaps track those 20-30 other keywords is via Google analytics, checking the traffic sources for your website.
So, to save you all the time RankWatch has an awesome feature, which helps you identify hidden opportunities i.e. it will suggest those keywords, which you are not optimizing, however are ranking well & should be suggested to your clients to consider tracking them as well. These will show up under the LHF page along with their broad-match search volume, their trend over a period of 6 months and their respected CPC’s.