Not my experience.Depends on the type of set screw. Hexagon head set screws are invariably 10.9, whilst socket head cap screws are invariably 12.9. Given the OP was looking for Hexagon head set screws it’s fairly safe to say that they are normally 10.9 . Only special application are normally supplied as 12.9
Specify a high tensile hex head set screw you get 8.8. 10.9 seems to be a special order. We use 10.9 hex head screws in one particular place in one of the machines we produce - sometimes difficult to get.
What's even more difficult is getting fitters to read the entire part note and not stop reading at the bolt thread and length, wander off to the bolt rack, get our stock 8.8 ones, install them and tighten to the higher torque specified on the drawing for the correct 10.9 . . . few months down the line after customer commissioning and there's a failure in the machine requiring some serious dismantling to get to.