Except it's not really "fires at 1800rpm", it's more accurate to say "can fire two rounds, 30 milliseconds apart" - a very, very, fast double tap. As you say, the idea was to get the second round down the barrel and away, before the recoil takes the aim off target. The USA tried to achieve the same effect with Project SALVO; guess what weapon it lead to?
The limiting factor in all of this is human reaction time; about 200 to 250 milliseconds between "brain decides to pull trigger" and "finger moves on trigger" - you can't really improve on that.
Yup. It all boils down to you can squeeze the trigger fifteen times on that setting and if you're good enough, hit fifteen different targets *before your magazine goes empty. The thing that always struck me as stupid with the AN-94 (as there was absolutely no need for it) was giving the thing an automatic fire capability. Why?!? All it did was add to the working parts' complexity. It never got a Product Improvement Programme like wot the Yanks gave the M249 when that was being a bit of a sod, mainly because the designer died in the mid-2000s and he wasn't around to shepherd it past the guys at Izhmash, who were already making the AK-74M and AKS-74U and probably didn't need the competition from an upstart who wasn't a Kalashnikov.
If he had been, a lot of the problems with the rifle could have been fixed. As it is, it's a dead-end that instead could have been the starting point of a really nice rifle around its A2 version.
On the Yankee gat? M16?
* With two bullets each.