The Saskatchewan REALTORS Association benchmark of $444,700 is a city-wide figure, and an automated model is essentially adjusting outward from averages like it. The limitation is fundamental to how automated valuation models work. They pull from public records: square footage, lot size, year built, the bedroom and bathroom count from the original permit, and recent sales in the area. If you added a bedroom, finished a basement, or upgraded the kitchen without updating the public record, the algorithm does not know.
For a home that has not been renovated and is similar to other homes in the neighbourhood, an online estimate can land reasonably close to market value. For a home with improvements, the gap can be much larger. The only way to know the real number is a hand-reviewed valuation from someone who has been inside.