The rightmost digit was dropped from the 200 series when they reset the generation (leftmost) number, but the market position identifier has been in middle of the model number since the Geforce FX (5000 series), and it's always had roughly the same meaning. So the Geforce 7600, 8600, and 9600 were the same market position in their respective generations as the 260, 460, 560, etc, were (and it's THAT SAME market position that the 1060 occupies for Pascal). As far as release schedule, nVidia release order within generations for many years have been top-down except for the 9 market identifier, which launches late in order to double-dip from wealthy enthusiasts who might buy both the 8 and 9 cards from the same generation.