"Until I am satisfied."

The actual amount of time varies widely. If it is a topic I am only casually interested in knowing more about (the winner of season 124 of American Idol, for example), the time spent searching is pretty minimal. Whereas if I am looking to prove my point, or win random trivia, I am likely to spend more time.

If it is business related, then I spend as much time as needed to satisfy the objective. For example, if I am looking for competitors for a new venture, I know that spending many hours researching is a small investment for the knowledge gained of the industry. But I would never spend 2-4 hours searching for a trivia answer. Searching for competitive keywords may add up to hours per month, but directly coincides with a return of my investment.

What are you really trying to find out? =)