How to define a satisfactory strength of pulsed magnetic field?

With regard to PEMF devices, it makes sense to use the ones which can be applied with different frequencies. Another factor would be using a bigger strength of magnetic field. I would define a satisfactory strength of pulsed magnetic field as follows:

Square wave, frequency 30 Hz, duty cycle 50%, the field should measure at least 10mG in the distance of 100 cm from the coil. Weaker fields seem to work much... weaker. The average power delivered to the coil is 300 - 350W (60 -700 W in an impulse). No wonder the coil gets hot quickly here.
To prolong the time of using the coil before it gets hot, I usually decrease the duty cycle of impulses down to 5 up to15 %. In real usage, we of course use different frequencies. Higher frequencies result in smaller current through the coil (due to higher impedances).

Of course stronger fields need much less time to get a desirable effect.

I estimate time needed to get a desired result as being between Contact and Plasma mode, much closer to the latter.
The big advantage of this mode is the fact that magnetic field, no matter what the frequency is, easily gets through the inside of cells, which is impossible for Contact mode at the voltages we use. The PEMF easily penetrates also the inside of the organs and the skull. It is very important in "emergency" cases.

For example, some time ago I realized I I had got the so called "stomach flu" - a really nasty infection. Such infections stupify people, I had suffered a whole day before I realized I should use Spooky2 system. I did a full scan, and then used found 5 top frequencies for an hour in the PEMF mode. It worked like a charm, the relief was instant, 90% of suffering was gone. The next day I repeated the procedure and forgot about suffering. Such an instant effect wouldn't be possible in Contact mode.

This 10 mG at the distance of 100 cm can be calculated as decently strong field of 0.1 Tesla = 1000 Gauss at the distance od about 2-3 mm (while using electrodes put/pressed against the body. The connected coil may get hot within several minutes. Using higher frequencies and, let me repeat, limited duty cycles (5 - 15%) increases the time a coil can be used before I have to replace it and connect another (cold) to let the previous loose the temperature. Using PEMF I usually use frequencies within the limit 10 - 5000Hz. However, for up to about 200 kHz the coil still works.