The two microwave ovens I owned are counterexamples to both these comments. The older on would precisely go 15s on and 15s off (when on 50% power) while the newer uses an inverter to actually reduce the microwaving power, and stays on 100% of the time.
Yeah but it is not 15 full seconds on and 15 full seconds off, it alternates much faster so the heat has the time to dissipate a bit.
Spoiler: that is also how LEDs dim and it works perfectly.
The two microwave ovens I owned are counterexamples to both these comments. The older on would precisely go 15s on and 15s off (when on 50% power) while the newer uses an inverter to actually reduce the microwaving power, and stays on 100% of the time.