I read Cal Newport often and I recently read about his new approach to managing his Inbox, where he has separate inboxes with separate email addresses for work, for his podcasts and for personal use. In moving from a single block of time for all email to multiple smaller blocks specific to each inbox, he claims to have reduced the context switching involved in going through all email in a single inbox.

Though I don't do this for email, I do this for articles / newsletters that I read as well as podcasts that I follow. And I do this for different types of tasks at work. 

The idea is simply to do more of the same in a given time block of one to three hours and use separate time blocks for different types of tasks. 

As long as the context switches are happening from one time block to another and not within the same time block, we're on our way to higher levels of productivity.