When I was a kid, a lot of folks considered a non-passthrough the ideal shot, just because they figured the broadhead would flop around inside and do a lot more damage. Then someone came up with the thought that having part of the arrow sticking out of the animal and slapping limbs and twigs as it ran would keep the critter spooked and make it run further before it dropped, and so a passthrough would be ideal.

Neither theory took into account that a wood or aluminum arrow would likely snap off on the first good obstacle it hit, so the broadhead wouldn't be thrashing around inside the chest nor would the arrow still be sticking out to keep spooking the deer and making it run further. Carbon arrows now, they're a lot harder to break so both theories might actually be workable for them.

I do like to have a passthrough so I can get double the blood trail, but I don't worry about it when I don't get a passthrough.