Use the Keyword Planner to flag any terms on your list that have way too little (or way too much) search volume, and don't help you maintain a healthy mix like we talked about above. But before you delete anything, check out their trend history and projections in Google Trends. You can see whether, say, some low-volume terms might actually be something you should invest in now -- and reap the benefits for later.
Keyword Discovery is a paid subscription service that offers marketers the ability to see keyword data across multiple search engines. They maintain one of the largest databases of searches, (nearly 38 billion) which are compiled from over 50 different search engines. The search data shown is a record of the number of times the exact keyword or phrase has been searched over the last 12 months across all 50+ search engines. You would assume that the search volumes would be much larger than any other tool because of Keyword Discovery’s access to data from over 50 search engines, but the fact that the keyword matching option is set to exact, greatly reduces the total volume. Unlike Google’s tools, Keyword Discovery does not collect or show data relating to paid search, such as Suggested Bid, Cost per Click, and Competition. Data is collected daily, but updated monthly. Although you must pay the subscription to have access to all the features, Keyword Discovery does provide a free alternative.
They also seem to be getting this wrong often enough that I've got less confidence that the keywords that make up these groups really belong there. I recently tried to check the volume for the keyword [active monitoring] (the practice of checking on a network by injecting test traffic and seeing how it's handled, as opposed to passive monitoring) and the Keyword Planner gave me the volume for [activity monitor] (aka Fitbit).
This database was built using data from BEFORE Google required active ad accounts to get good keyword data & before they started blending data together for similar terms. Even if you set up an AdWords account and spend significant sums of money with them, they may require you to run your ad campaign for 3 or 4 months straight before they will show reasonably precise data instead of exceptionally broad data ranges.
In fact, Google Suggest is the best way to find good long tail keywords that people use to find information on Google. Google admits that while Google Autocomplete (another name for the Google Suggest feature) was not designed specifically for marketing, it can deliver meaningful insights and help stay on top of trends. There are also many clever ways to use Google Autocomplete that can help you with SEO.
The limit on manual keywords could be higher. I personally wish we could input 10,000 keywords at a time, instead of 200. However, I understand the costs that Long Tail Pro has to maintain each time a new manual keyword is input. Not a deal breaker, I just wish the limit was higher. (To be fair, I don't think most keyword tools have a bulk manual option at all).