Amplitude
The measure of the amount of rotation in the swing of the balance wheel, in either direction.
Amplitude is higher when a watch is lying flat and usually falls when the watch is in a vertical position, due to increased friction. Amplitude can also fall as the watch winds down and the mainspring delivers less power.
Amplitude is a good indicator of the movements health and if is too high or too low, or that changes too much in different positions, can indicate a problem with the movement.
great : 270-310
acceptable : 250-270
If higher / lower?
Ask for a different watch or have your watch serviced