What I found interesting is how much of the social network's personality came out in this one piece of data. LinkedIn's business-focused go-getters are most engaged just before and just after business hours, but they avoid deadline-heavy Mondays and Fridays. Facebook, Twitter, and Pinterest get the most activity during mid-afternoon, when office workers take a break post-lunch to check in on their personal lives. Coincidentally, this is also a great time to send email campaigns.
Useful information if you know your target audience well. Are you offering a welcome distraction to feed afternoon daydreams, or are you offering a life-changing business opportunity? Choosing the right network at the right time can help your message get to the right eyes.