I think there's alot of variables to describe this, and it varies depending on rifle being used, cartridge, target size and technology being used also.
For me, shootin prarie dogs with a little 223 and .2 BC bullets, long range begins at around 300 yds. It takes known distance, dialing or hold, and good wind doping beyond that. But for more modern bullets with higher BC's, long range on prarie dogs begins somewhere in the neiborhood of 400 to 450 yds, depending on the caliber and scope being used. Anything beyond 400 means holding off some to make consistant first round hits, so dialing/holding something is almost a must. Anything beyond 400 also means a 10 mph wind is blowing the bullet off by 2 or 3 "dogs", so that requires some adjustment too. In addition, even on calm days; consistant hits at 400 and beyond require a sub 1/2 minute rifle that will shoot that way all day long, hot barrel or not.
This is just me, others will have different opinions I am sure. Heck, I've heard it said on this site somewhere that 500 yds is point blank range, and LR doesn't even begin untill 600+..? I don't know of any cartridge that when zero'd for 200 or even 300 is still "hold on hair" at 500.........unless they're talking about Elk/Moose size hair and high BC bullets going 3500'/sec or faster.?