Networking Okay During Work Time

depending upon your organizational culture.
I know organizations, both governmental and business sector, where no deviance from the "nose to the grindstone," is tolerated. For example, you cannot use your office resources or time for personal use at all, period, you will be terminated with extreme prejudice if you do. You cannot take more than 60 minutes for lunch or else. To me, the focus here is on accountability,and in the case of government, good stewardship of the tax dollars.
I know of other organizations where the focus is on results. Where it is fine to do as you say as long as you get your job done. At the far end of the spectrum are those cultures such as in the banking and utility professions where civic involvement is practically a performance objective because it brings back positives to the organization. Where you can use organizational resources that don't directly relate to the bottom line, but do bring indirect results (Think printing off a meeting agenda for a volunteer organization or taking time to raise money for a worthy cause.)
Will I read an HBR article at my desk during the day? Yes. It only takes a few minutes and I do it in between tasks, almost as some took cigarette breaks in early generations. It helps me shift gears, frequently motivates me, and occasionally provides me with information that makes me more effective.
Will I sit at my desk and read Mark's forthcoming book in one sitting? No. That I'll reserve for other times such as when I'm flying, eating lunch at my desk, or late in the day when I've finished the day's "Next Actions," list and I have prepared the one for tomorrow and staying in the office helps me avoid heavier traffic home. (Although,after re-reading that last sentence, perhaps I should read a book on sentence construction.)