Every page title should refer to the content of that very page. If you have copy about "rocket ships" on the home page and want it to rank for the query "rocket ships", then use that phrase in the title. If you have an internal page that is all about "rocket ships" and would rather see that page rank for the phrase, then put the words in that title.
You might also do both, if you want to see both pages rank -- and both pages have good "landing page" style content for the phrase in question. Just make sure that your title describes the page where it appears.