Yes, the breached wall is an excellent example where you can see this behavior in action. It is my habit take out the towers and then march crossbows up to the breaches. For this, you want to put them in a longer narrow box.

If you watch them, you will see some shoot straight, some of them shoot up in the air, and some not shoot at all depending on whether they are blocked by the walls. You can see the line of demarcation fairly easily when the guys who are shooting squat to reload and the blocked guys stay standing.

The guys in the back of the box will still shoot straight if they are not blocked by the walls. Apparently, they are capable of shooting between the heads of the ranks in front of them.