Experience from people in the circle of acquaintances who, shortly after the commissioning of such islands, are looking for ways to retrofit a splash guard. But it certainly depends on the depth of the island and what one understands by "frying". There are quite some differences, in my experience :)
We ourselves are not island fans and are currently planning an open kitchen, but two-row with a half-high wall.
You might think these people hadn't cooked or fried before, but only started with the island ;)
But everyone has a different perception.
Of course it splashes, but not twice as far to the back as to the side.
You can estimate yourselves how far it splashes to the side, do you know how far it splashes to the back (always to be measured from the edge of the pan)
Regards