If you have a minute, check out this article from The New York Times that came out sometime last month:
Since many of us use the Standard & Poor’s 500-stock index as a proxy for the market, let’s take a look at the period from 1950 to 2012 to see how often we’re likely to feel positive, based on how often we check our investments:
If you checked daily, it would be positive 52.8 percent of the time.
If you checked monthly, it would be positive 63.1 percent of the time.
If you checked quarterly, it would be positive 68.7 percent of the time.