The mill rate itself is set annually to cover the municipal budget, the library levy and the provincial education portion together, and it moves based on what the City needs to collect, not on how any one homeowner feels about affordability.
A bill that feels high is sometimes a genuine assessment error and sometimes simply a reassessment catching up to real market movement after a full revaluation cycle, and those two situations call for different responses, one an appeal, the other an adjustment to expectations.
The only reliable way to know if your specific bill is out of line is to compare it against genuinely similar Saskatoon properties, not a general impression. Get your hand-reviewed valuation from Joel Dyck.