The 270 kts limitation is only applicable after deicing with type 2 or 4 fluids. Otherwise, .82/340 is the max speed.
Some guys don't fly above 300 because of cockpit noise.
For a while we were limited to 300 when using speed brakes.
Cost index 35 (used by some) will give apx 280 kts during descent.
If I am limited to 270 (or any other speed) I will inform you. If my descent speed is 280 (but not limited to), I will not.
What do you consider to be "normal" speeds during descent?