Most will print every copy at once, switching between them.

It also often works better because doing small parts can overheat the plastic. Moving between copies lets things cool down.

It can be useful for circumstances where you want to minimize (or even eliminate) retraction. I've done some cool prints in vase/spiralize mode with large nozzle sizes -- with zero seams, zero retractions, and zero moves over printed surfaces, you can get some really awesome looking prints.

But anyway it was just an example of a scenario where the slicer might not have enough information to know how to not crash the print head.

Almost noone does this, though. But, even then, you have all the information you need in theory because you're putting down the plastic.

FDM slicers usually don't have the information about the dimensions of the print head. Yes, it is a rarely used feature that is only supported by some slicers, but I just mention it as an illustration of the similar issue that exists with CNC machining.