The authors of The Lean Enterprise talk about the difference between radical process changes and incremental process changes:
We should explore and experiment with radical process changes—known as kaikaku in Lean terminology—in the same way we explore potential new business models.
We should try them out with a relatively small, cross-functional part of the organization, with people that fall in the “innovator” category. These people must be interested in the proposed process experiments and have the necessary skills to run them. For a change that proves to be valuable, this team can help other groups adopt it so it “crosses the chasm” within the wider organization until it becomes the standard way to work.
However, process improvement does not stop here. All teams will still make continuous, incremental process improvements, known as kaizen, as part of their daily work to reduce waste and increase throughput.