Some of the best shots I have ever made have been on backyard bunnies. Small target to start with,so your focus and concentration are already at max, and no pressure. If you miss, its no big deal, if you hit you are sure to find it. With big game, the pressure of a good hit is always somewhere in your mind. And we all know what can happen even with a good hit.
It is the best practice you can get. Not a wasted shot, but rather another mental picture of a beautiful arching arrow hitting its mark. File it away and use it next fall, and the year after...
Gosh, I`m heading for the creek bottom next to my house. Got to be a bunny sitting in the sun somewhere down there.