How much time do you special social networking on My developerWorks each week?
And how much time do you spend social networking on other web sites each week?
as probably most people, I use social networking when I see personal value of using it (compared to traditional options like e.g. email or telephone), not just because everybody does. I agree with John that it is not easy to express the usage of social networking in hours and minutes. I find it more interesting to understand the strengths and weeknesses of each tool (like e.g. Twitter) and to use it in the best possible way, e.g. avoid large email attachments and use online file sharing instead.
For example, I use blogging in combination with newsletter - like you do with your dW community snapshot - to keep the newsletter small and clear and conduct traffic to the detailed information in the weblog. In my free time, I have been using free wikis to organize an event together with friends and to set up a private community. This saves a lot of email traffic and keeps everybody up to date.