Not long ago, I had the fortune of listing to a recorded conversation 
between David Allen and Tiago Forte. While I am deeply familiar with the former, the latter was a new voice whose ideas on productivity caught my attention. Tiago is the founder of Forte Labs, a productivity training firm and consultancy based in San Francisco. He helps people envision and prepare for the future of work using a design-centric approach to productivity. He is definitely at the forefront of efficiency thinking and someone who I intend to follow more closely. I strongly suggest checking out his blog at: https://medium.com/forte-labs In particular, I recommend reading his posting:
Efficient Librarian 