Insulation Power Factor at Nominal Hertz (Hz)

It would but the magnitude would depend on the insulation materials, temperature, etc.

If you are dealing with oil-paper insulation such as in a condenser bushing, for example, at 25°C I would think the power (dissipation) factor should be about half that for one assemblied with properly dried paper and degassified oil.

The primary value of power factor measurements is comparison. That is, measure and record the power factor of new equipment when it is initially installed then periodically repeat those measurements under the same test conditions as the original measurements and compare the results. Those measurements will often allow one to recognize degradation and take action before the equipment fails.