I can see the overlap, and yet at the same time... Logical Unit There's a strong argument for bundling library code with its benchmark, examples & tests. Logically speaking, this is a single logical unit, and the benchmarks, examples, & tests are "satellites" of the library. This single logical unit happens to be called a crate. Work Unit Similarly, after making changes on a library, it's quite natural to first ensure that the changes on this library are sound (in isolation) by running the te...