How has knowledge from one program carried over to another?

At NASA, it's common for engineers to support multiple programs over their career.

As you mentioned, I started working on the space shuttle, but my career has spanned other manned missions, science and planetary missions as well.

If you're an engineering discipline, like flight mechanics, for example, you provide the mission designs, you develop simulations and models, you perform analysis for all the different phases of a program's lifecycle.

And you do that repeatedly for all the different programs and projects over your career.

Every program you support, you gain understanding of all the systems and the components that make up that flight system.

You learn how to solve problems with specialized tools and methods tailored to solve that program's unique challenges.

So how do you ensure it doesn't get lost?