Periodically, GE releases new Application versions, Service Packs, SIMs or Hotfixes. For the purpose of this discussion consider SIMs and Hotfixes to be the same.
While it is important to keep your applications up to date and appropriately patched, there should be a reluctance to apply the latest patch immediately upon release. Sometimes being the "first car off the lot" is a bad idea when it comes to new patches etc. Read through what the patch is fixing, and the decide if it applies to you and your environment. Many patches will not apply to your environment and can wait until another "accumulated" SIM is released.
Most Service Packs and upgrades have both a Server and a Client piece to it. Plan on upgrading both your server and all of your related clients at the same time. Often, but not always, clients won't connect if they are not of the same version.
Having said that, the site should plan on upgrading to one of the latest SIMs once or twice a year. It should be tested in the Dev/Test environment and if successful apply it to the Production environment. If your company has many sites with GE Plant Applications installed, try to keep them relatively in synch as far as Versions, Service Packs, and SIMs go as it makes troubleshooting and support for the environment more consistent.
For Plant Applications/Workflow the SIM will write data to the database and will require that it is executed with a user that has sysadmin rights.