To have a stable and effective system support at all time the organization, requires an excellent knowledge management, where the persons handling the job are well equipped with the knowledge that requires to carry out the job. In case of in house staff, it has some limitations. As in case of some specialized task , the organization relies only on a single resource because one can not keep several redundant resources for every task at all times.
The best way to get out of this situation is to outsource that job to specialist organization.