Mmh not so sure. I think each sensor has a sweet spot.
For instance, for 70D this is 1600, while 5D3 should fall somewhere between 1600 and 3200.
[Sweet spot = break-even point where amplifying in-camera the signal more starts leading to a lower SNR (Signal-to-Noise Ratio), I think mainly due to sensor read noise being amplified as well.]
Googling should help.