I agree with the parent poster. I've spent 6+ years at FB and the whole time I've just worked on what I thought was important. No one was ever assigned a project to me. The process normally involves managers and PMs highlighting problems and potential solutions and then developers picking projects that interest them. It sounds crazy but it is a controlled chaos. We incent people to work on non-sexy work by aligning with performance reviews. So everyone is required to show some better engineering impact (like writing documentation, unit or integration tests, cleaning up deprecated code etc).

It's the longest I've stayed at a company (worked a decade at startups and web dev companies) because of the freedom to constantly work on things that are interesting. For example I've changed the type of developer I am twice since joining.

So if it's worth a look if that's a style that works for you.