If Zebby starts Tuesday, they don’t need Varland on Wednesday or Friday. Ober Wednesday, followed by SWR, Festa, Lopez, Zebby has everyone on regular rest.
However, if they want to give everyone an extra day, they could slot Varland in on Wednesday as you suggest, but that would be choosing Varland over Ober. More likely, Ober would still go on Wednesday and Varland on Thursday.