I leave the chest buckled on all of ours, and I leave them fastened all the time. Those are a big hassle otherwise. They all will just stick their heads through when I hold it up. Well, except the pony. I lay hers up on her neck and pull it down over her head that way.
The buckle too loose. I could re-stitch the strap postion but I'll mess it up for another horse whereas I can rip the threads at the seams. That's what we came up with anyway:')