For snubbing (plate) transformer leakage inductance, I connect 1kHz square-wave to primary at a few volts peak-peak, and then scope the secondary with no load. You can see overshoot or undershoot and adjust the snubber values.
Measuring inductance, resistance and using math did not work I found because the winding capacitance is coupled to both the windings, and core, and is not easily known. It also does not tell you power dissipation in the snubber resistor.
Example 120VAC to 1,250VCT 300mA transformer (Hammond 720X) which is about 1:10 turns ratio.
I found 0.01uF 3kV and series 1k ohm across each secondary winding works best, I used two sets total four parts.
This is to lower stress on rectifiers and lessen switching EMI.
For audio transformers, the technique also works.