This sounds like a chance for a bit of a challenge shoot.
I too am pretty convinced that the vast majority of deer stalkers, using their stalking rifle, their stalking scope set on a reasonable stalking maginification, their stalking zero, their stalking deer legal ammo, prone off a bipod with no additional support etc. couldn't put 3 shots into a 1 inch circular bull at 100 yards. I am also certain that I couldn't, I'd consider myself lucky if I got 3 shots in a 3 inch bull. I also suspect that HWH is pretty well qualified to comment but maybe this is just bias because I believe him to be correct.
I don't of course dispute that there are people who shoot a lot or are naturally talented and who could achieve this it is just that everyone on the internet shoots sub-half inch groups at 100 yards "all day long" whereas the shooters I meet in the real world don't, and if they do the group isn't centred on the bull. There are two conclusions here, either most people shoot a lot better on the internet than they do in real life or everybody I've ever met shoots a lot worse than the members of SD.
I think the red bull on the "Shoot n See" targets is 1 inch so maybe we could organise a bit of a competition. You travel to your normal stalking area, stick up a target with a 1 inch bull, take out your normal stalking rifle with your normal stalking scope set to a normal stalking magnification, go back to as near 100 yards as your ground will allow, (some people don't have ground with a suitable firing point and safe backstop to allow an exact 100 yard shot) load up 3 of your normal stalking ammo, settle yourself in the prone position on a normal bit of your normal stalking ground with only a bipod allowed for support. (I guess you could also shoot sitting or standing or prone off your elbows but nothing MORE than a bipod is allowed, I think most will understand what this means in respect of taking a stalking shot.) Then you shoot 3 shots and photograph the target and submit it. There is no need for measurement or similar, this is just for fun. You act within the spirit of taking a stalking shot so...
YOU DON'T - shoot 50 targets until you get a lucky one with the 3 shots in the bull. Shoot 10 "fouling shots" at different targets until you eventually get one in the bull to start you off. Shoot any more or less than 3 shots unless you want to submit targets for more than one load or rifle just for your entertainment. Practise on other targets first to get your hand in the way. Change the zero on your scope so it is on at exactly 100 yards - for example I'm zeroed at 200 yards and so will have to aim approx 2 inches low at 100 and as I can't see the other lines on the target with my scope at that distance I'll have to guess just like with a deer. Modify the target so the exact aiming point will be marked such that your shots will hit dead on the bull at 100 yards - deer don't have such an aiming point on them but I guess most targets usually have some sort of grid or markings on them and we just have to accept that and if you can see it with your scope at the normal stalking magnification then I guess you can use it. Use a bench with a range of sand bags and the like. Eliminate targets because there was a gust of wind, or you pulled a shot, or you hit a bit of grass, or your mate sneezed just as you fired, or the wind blew the target and it moved slightly, or your elbow slipped on the grass, or for any other of the common reasons we find people using to cover up the fact that they actually shoot a 5 inch group to the 95% confidence level but they choose only to show the occasional exceptional ones.
Maybe we could just use a one inch circle on a white page so everyone with a non-100 yard zero is having to aim off with no guide just like when shooting a deer? Perhaps we can refine the requirements and then post on another thread?
Then you stick the photo of the target up here along with info on the rifle, scope, magnification, exact distance if you know it and maybe even ammo or load info just for interest.