3 evenly paced shots is still an accepted distress signal, although obviously someone has to be paying attention.
Off the top of my head the only time I recall 3 shots at a big game animal was when I took a pretty new hunter out for bears. I've spent lots of time around black bears and grizzlies, but black bears are far more numerous, so I was always a bit cavalier with them- I see them almost daily and it's not uncommon to walk out on the porch and run into one.
This time, the hunter made what I thought was a good shot at about 60 yards, and the bear lost it's footing for a moment. I was expecting a short dash towards the timber then he would drop, but this big male bear must have got disoriented, because he started running straight down the hill towards us! It was at that moment that I felt I was indeed a bit cavalier with bears because my rifle was still slung on the shoulder. I pulled it into action, dropped to my knee and ripped off 2 160gr Barnes X bullets from the 7RM, which dropped him ASAP. I guess it sounded like this- BOOM..........BOOM..BOOM!
Post mortem showed the first shot was a good one, and both my shots hit him in the front chest and shoulder area. I don't count this as an actual charge since the bear never got within about 40 yards of us, and I actually think that the initial bullet just turned him a bit and he decided to run downhill, not planning on an attack although I'm sure he would have run right over us given the chance. I really don't think he even knew we were there when he decided to run.
Other than that, I don't recall more than 2 shots and maybe a finisher.