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I've not had any issue with making archery range, setting the direction on desgination and assigning a squad to train on it, myself. Well, outside of eating through bone bolts like no tomorrow. Not tried multiple ranges either, I found one was more than enough for a squad to each each other and rotate a bit with some live training.
wait wait wait .. I don't need an archery range for every target? .... just for any group in which the fire direction is all the same?
You'll need to set one up for each of them if you use multiple of them, one can't serve multiple
I was just speaking of personal experience, they takes turn training one at a time at the archery range and teach each other how to shoot. Those that lucks out of training gets to practice live firing when it happens. If you need really fast training, then multiple archery range up and assign enough to keep half the squad busy constantly, more is a bit of an overkill with how dwarves takes turns.
It's still gonna chew through bolts, I had hard time keeping up with overabundance of bone.
Maybe if they can access it from the back? That would count as being walkable.
The wiki says that channeling out (or otherwise) in front of the target will recover bolts.
Maybe, I've never bothered to try it that way. All of my archery targets are against walls, so I can at least verify that channeling their sides out helps bolt recovery and channeling front of them stops training. It's not really worth the effort and I suspect that it's line of shooting, rather than walkability, but you can test it out