Saskatoon's own resale market runs tight, at 1.63 months of supply, and a similar undersupply shows up in the rental market. An empty suite is lost income the moment it sits vacant, since a landlord still carries utilities, insurance and the mortgage whether or not a tenant is in place, so most owners fill a vacancy fast rather than sit on one.
The exception is a unit mid-renovation, or one an owner is pulling off the rental market to prepare a house for sale rather than re-rent, which can look like warehousing from the outside but is really a timing decision tied to a listing.
If you are weighing whether to keep a rental suite occupied or empty it before selling, that decision changes what a buyer will actually pay for the property. Get your hand-reviewed valuation from Joel Dyck.