Not sure if there are motor with core bellow saturation. From what I see people terminated the coil power when voltage curve to the coil already flat.
Stingo will change frequency upon load, the hand become the load that change frequency. Yes, hand act as capacitor. Some health device do not account for this and while they claim to produce some magical wave, in reality, they only produce DC when people use it because of capacitor effect.
I think we need to define our terms of saturation
I believe you are referring to the point where the maximum current is seen in the coil. Normally a motor as a huge amount of iron when compared to the copper, in this case the current limitations prevent any more flux from being present in the iron. Increasing voltage would in this case allow more current to flow and more flux in the iron. I consider that this is a condition where the flux is not saturated but limited by current
I am referring to the point where any increase in current will not cause any more flux in the iron as the iron cannot hold any more flux within it. Even if we double the current the flux would have to find a path external to the iron core as the iron is saturated with flux.
This is important because at this point any increase in current will not give an increase in transformer effect or magnetic force on the armature but would be a waste of energy.
The iron is useful in causing the flux to follow the path we want but it is limited on how much it can carry
I could be wrong but this is my understanding of it.
I believe running the iron close to its saturation point may assist in transforming the AC transformer action into an offset DC sign wave where the voltage does not reverse polarity.
We run the motor in attraction because the flux remains within the core maximizing torque and transformer effects.
If we ran the motor in repulsion much of the flux would find another path and not pass through our secondary (compensation) coil reducing the transformer efficiency and torque. In normal motors we could possibly get more torque in repulsion mode.
An attraction motor does give stronger transformer effects.