I’ve personally never encountered such a poorly designed induction hob. Induction hob require proper electronic control systems to operate, it would be weird to design such a system to operate with a wide PWM, it’s costs nothing for the system to operate at 1Hz or higher.
In ceramic hobs, they usually don’t have proper power control systems. They normally rely on a set of thermal switches to disconnect the main heating element when the ceramic element gets hot enough. The entire control system is analog and relies physical phenomena like wax expansion etc. Phenomena that is well know to be unresponsive, but very cheap.
My induction hob does similar on low power settings (at the lowest it's something like 1 second on to 4 seconds off). On higher power settings it's not noticable. I suspect the main reason for this is it's often harder (and more expensive) to design power electronics to operate over a wide PWM duty cycle efficiently, so the low-speed cycling is a way to provide the low settings without a significant cost increase.
In ceramic hobs, they usually don’t have proper power control systems. They normally rely on a set of thermal switches to disconnect the main heating element when the ceramic element gets hot enough. The entire control system is analog and relies physical phenomena like wax expansion etc. Phenomena that is well know to be unresponsive, but very cheap.