Start from net operating income rather than a target percentage: gross rent minus property taxes, insurance, utilities not covered by tenants and vacancy, compared against what similar income properties have actually sold for through the Saskatchewan REALTORS Association's data.
Legal suite status changes the math directly, since a lender will only credit income from a permitted unit under the City of Saskatoon's rules. A pre-purchase home inspection, typically $400 to $600, and legal fees of $800 to $1,500 are real costs that reduce first-year return and belong in the calculation.
A number pulled from a different market or a generic rule of thumb will not tell you whether your specific property actually works. Get your hand-reviewed valuation from Joel Dyck.