The author basically introduces the importance of prototyping all along the design process. It will help designers keep iterating the product, and every iteration helps improve the product during each stage. However, it reminds me of a test, during which students are divided into two groups from a ceramic class. One is required to make one object during whole semester and final grade will be given on this work. The other is required to make as many objects as possible and their grades are based on the final amounts of works. The final works of the first group are typically not as good as the second one's later works. The reason is indicated in this passage. The first group spend whole semester make the prototype and make it at last day, which is the very first stage prototyping. They don't have the chance to do iteration during the whole making process like the second. group.

That's why design is a group exercise. As said in Lean UX, "All disciplines are represented, including any subject matter experts that could have vital knowledge about your project". Besides, according to the statement below, I learned that the design strategy should also be coordinate with business strategy. Thus, this chapter is a good complementary opinion towards Lean UX. A preparation period should not only include experts with related knowledge, but also involve management level which can ensure that the design plan is agreed with business's goal, in order to avoid further discordance and excessive documentation on communication.

For the contextual inquiry, I agree it is worth your time to do the field work and view context in order to truly understand what users do and want. But I still believe that in stead of spending months to do the ethnography and waiting for a long time to catch a "magical moment", maybe it is better to spend several hours to create some proto-issues first. It might help adjust the critical issues and gather as much target data as possible rather than gather tons of rich but trivial information.