This was an interesting question that came up on our Keywords Analyzer forum that I replied to over there - and I will paraphrase my answer here:

The question was asked as to how many actual Keyword results you look for when trying to work out whether to use that keyword to optimise a page for SEO purposes..

What I would look for is the actual search count in conjunction with supply and demand data which is shown in Keywords Analyzer as either R/S or KEI.

So, if you are looking for keywords to optimise pages for to get traffic you would ideally look for keywords that have as few competing websites for that keyword as possible. I find the optimum way of doing this is firstly to go to settings>campaigns and check the box that says “Get results in quotes” and this will then compare with Google pages that has your target keyword phrase matched.

Then run your keyword search.

When that is done start first by sorting by either Low R/S or High KEI to show you what the better keywords are in terms of demand and supply.

As for how many searches per day - this is where you need to exercise your own judgement in the context of the market you are targeting - so I would not like to give a hard and fast answer on that.