Multiple Keywords or Single Keyword focused?

 You need to start with the answer to two other important questions:

1. How many of these keywords carry the same visitor?

2. How competitive are the targeted terms/phrases?

Single keyword targeting works best only If a keyword is highly competitive. This is not only because you can maximize on-page optimization, but also because it means that internal and external links that point to the page can focus more directly on the target term/phrase. It's also likely that you'll be competing against pages that are more highly targeted on that keyword phrase and could lose out if you don't have that singular, pinpoint focus.

 In a scenario where every shred of keyword usage matters a great deal, from the anchor text focus to the keyword being employed at the very start of the title tag, breaking up keyword targeting to multiple pages can make a great deal of sense.