It depends at which level you're at. If you're working at an infrastructure or firmware level, throwaway work can be expensive and time consuming. Re-architecture can also be time consuming. There are some parts you have to spend design cycles on, especially if you're doing a large project. It's not that you can't pivot, but the pivot takes a lot of time. At the very least have a set of System Features and System Guarantees that you will drive towards.
With embedded development it's entirely fine to iterate fast and throw away work, until the product is shipped. And in certain applications it is fine even after it is shipped.
