Many organisations know how to start their process improvement (with an assessment and some training) and have a reasonably good idea of what they should attempt to achieve. But then, the consultant who assisted them at the beginning goes away and they start sinking into the details of every day life.
The PI check-up is a regular intervention in which an independent adviser will come and spend an average of one day per month (usually two days every other month) to review the improvement effort so as to re-direct the effort in order to ensure that the focus on the long-term benefits because of the short-term pressures.