The City of Saskatoon sets assessed value on its own cycle, and residential property in Saskatchewan is taxed on 80 percent of that assessed value, which is why a buyer's own market-based offer often lands well above or below what the tax notice shows.
A successful appeal can lower future property tax bills, which is a genuine selling point to mention to buyers who ask about carrying costs, but it will not move the sale price itself, since buyers and appraisers price the house from sold comparables, not from the assessment roll.
If you think your assessment is wrong, filing with the Board of Revision is worth doing regardless of a sale, on its own timeline. Get your hand-reviewed valuation from Joel Dyck.