The idea behind “easy to pickup” (applying mostly to books) essentially comes down to the books attraction in being read from anywhere in the book. Don’t have to start in chapter 1, and work your way down.
Often it is your “comfort books” that lend themselves to be easy to pickup. Books that have short chapters are of course easy that way. e.g.: Jon Winokur’s Zen To Go, and The Portable Curmudgeon are my favorites of this genre.
Perhaps more books must be written to be read like this.