Kathy Sierra hit the nail on the head three years ago when she introduced the concept of the Asymptotic Twitter Curve. She links to some excellent essays that suggest we're not doing ourselves any favors by letting our attention be divided amongst myriad bite-sized nuggets of information. Go ahead, read her post and follow a few of the supporting links. You'll be glad you did.
If it's possible, the temptation to avoid entering "the zone" to focus deeply on one subject has gotten worse since 2006. The success of Twitter has spawned similar microblogging sites and caused other sites like Facebook to make activity streams their main focus. Media and websites have become very proficient at vying for our attention.
It's a good idea to occasionally evaluate how we use our time. If you think there's room for improvement in the way you allocate your time, Leo Babauta wrote a short wonderful article called How To Reclaim Your Attention.
All of Leo's suggestions are good ideas. His sixth suggestion, give your attention to the important, is so important that it bears a little more encouragement. Daniel Steinberg wrote an article, Kill, Commit or Transform your Projects. While the title seems a little dire at first blush, the action of triaging some projects to fully commit to others is invigorating.
What is it you want to accomplish?