Most convenient ice near me is city water sprayed out of an elaborate plumbing system on top of a sandstone cliff. When I examine this ice, it appears detached and or pocketed in certain areas. I read a short article, https://m.petzl.com/US/en/Sport/Waterfall-ice-study?ActivityName=Ice-climbing that makes sense to me in that water running down the rock face separates the ice from the rock itself. Does this happen in nature often? Frozen waterfalls appear to have the ability for better quality ice over a farmed system of layered/intervalled ice. Thoughts on climbing farmed ice? I did put a few screws in my local ice, finding hollow layers in half my placements. Also, leading this popular top-rope area doesn't have the call of some amazing looking natural climbs I'm eyeing up. Minnesota by the way.
In my limited experience, "sprayed on" ice can indeed be weird. But if the farming process allows the water to run down the surface and freeze as it goes, then you get a very natural type of ice. Most any type of ice can have air pockets; it's a judgement call as to whether these render the screws unreliable.