Workunit Maintenance

I'm not sure if this is quite the right place for this questions, but here goes.  I have a few questions about how you handle maintenance/clean up of your workunits? 

• Do you keep a certain number of days? 
• Do you use a process flow to delete workunits?
• Do you delete activities and variables separate from workunits?
• Do you use a process flow to delete the related action requests?

Every time we go to do a big upgrade we run into issues with the size of our database and related business classes on the Landmark side.  I would appreciate any info you are willing to share.

Thanks,

Jessica