I'm looking to build up a “tool-box” of strategies/techniques/habits for reading non-fiction effectively and efficiently.

My literal tool-box sometimes consists of multiple versions of the same material/book, specifically for technical books.

Either hard copy of the book plus individual chapters downloaded from subscription service (in some cases every chapter of a particular book) or hard copy of the book and purchased Ebook version. I don't have a hard copy for every electronic version, but if I particularly like/want for extra reinforcement the physical copy, I'll make space for it. I only do this with technical books, I've rarely (intentionally) bought a print version of non-tech non fiction or fiction for the last 2 years.

Three benefits: 1. Convenience/portability: I don't want to lug a physical copy certain places, especially the really big ones. 2. Reinforcement: Call me old school, but certain topics, I know I'm not going to mentally synthesize in electronic format. The multiple formats helps solidify those topics. 3. I'm a heavily linguistic learner, so the multiple versions is exciting.