None. Zero. Zilch. Nada.
Rank tracking is a complete waste of time, software dollars and search engine resources and should be completely avoided unless you have naive customers that insist on running those stupid reports to prove you've done your job.
Everything you need to know you can get from a good analytics package and that's where you should invest your time and money, along with educating those naive customers to do likewise.
If your rank goes up you'll see traffic in your analytics and likewise, if your ranks go down, you'll see a decline in traffic.
Heck, I rank in the top 10 for a high volume of terms (thousands) but some of them don't generate traffic and others that do generate traffic don't generate money.
Your ranking report won't tell you that and you'll just waste time working for position instead of working for ROI.
Analytics, that's the game.