What varies is the assessed value itself, and the Saskatchewan Assessment Management Agency reassesses on a multi-year cycle using mass appraisal, so two houses on the same street can end up with different assessments if their recorded condition, size or improvements differ. That is a data problem, not a rate problem.
The bill is split between the municipal mill rate the City of Saskatoon sets and a separate education mill rate that funds school divisions, and both apply to the same taxable assessment, which is 80 percent of the property's assessed value under provincial rules.
If your own assessment looks out of step with what similar homes are actually selling for, that is worth checking against real market evidence before you assume the system itself is unfair. Get your hand-reviewed valuation from Joel Dyck.