The two grounds that actually succeed are a valuation problem, where recent comparable sales show the assessed value is out of line, or a factual error, where the roll lists the wrong finished area, room count or property class. A belief that taxes are too high citywide is not a ground the board can act on.
You can appeal every year a new notice arrives, but Saskatchewan reassesses on a multi-year cycle rather than annually, so most owners only see a meaningful change in assessed value once every 4 to 5 years. Filing in a year when nothing changed rarely produces a different result.
Knowing whether this is one of those years is the real question before filing anything. Get your hand-reviewed valuation from Joel Dyck.