The biggest waste in product development is re-learning.
Product development teams are large and diverse. When someone on the team learns something, that knowledge needs to spread quickly to the whole team. Otherwise, someone else could learn an opposing truth and the two people could begin working at cross purposes. The re-learning process can also span time. What one part of the team learns earlier in the development process could become important to another part of the team later. Spending time and money learning the same thing multiple times is a waste of opportunity and a potential source of contradictory decisions.
Learning from Lean. Kent Beck.