Saskatchewan uses possession rather than a closing date, and the exact hour on possession day is negotiated in the offer, commonly early afternoon, to give both lawyers time that morning to confirm the mortgage funds arrived and registration went through cleanly.
If registration is delayed, even by a few hours, possession is delayed too, since a lawyer, for the standard $800 to $1,500 closing fee, will not release keys before confirming the buyer legally owns the property, and that protects both sides from a deal that looks done on paper but is not yet done in fact.
Building a little flexibility into moving day plans, rather than assuming keys the moment the calendar date arrives, avoids most of the stress people associate with possession day. Get your hand-reviewed valuation from Joel Dyck.