Garrett currently works with Slack's designers to create Slack Kit, their product design language and UI framework. He has spent a good chunk of his life working within the nooks and crannies of software engineering, business development, product design, and user experience. After doing many of those things at Mapbox and Opower, he now leads design systems engineering at Slack.
In terms of being a better engineer, Getting Things Done looks about as generic as it comes, but it teaches core fundamentals of time and project management that every engineer should know. At a senior level, engineering is really just project management and setting expectations. This book was incredibly helpful in starting to operate within those parameters. Garrett Miller