I have worked for, or applied for several agencies in the federal government. It would be a cost saver and a team building experience to have the personnel security divisions to share the security checks and clearances information.
A central area to store the information would make it easier and quicker for personnel to be hired and on the job.
It can take up to a year to get some clearances done, so it would not make since for the same employee to undergo that again if they change agencies.
Also, if that person has a higher level clearance from the losing agency, it makes no sense to run a costly check on them at the gaining agency.
Employees with high level clearances would need to keep the information current (yearly). Employees that have stayed in the same level (below Secret) clearance should only need to update their information if they are transferring betwwen agencies or have a break in service over two years.
I am just attempting to save a lot of taxpayer money as well as make the hiring process much smoother.