tl;dr:"The biggest mistake I see engineers make is doing too much work on their own before looping in others." This costs time and creates the risk of going down the wrong path. Managers can help: (1) Encourage engineers to show work as quickly as possible. (2) Help them decide what to show that provides meaningful feedback. (3) Encourage launching something end-to-end internally, quickly. (4) Encourage constructive feedback & watch for toxic feedback, which discourages iterative development.