It's funny that the ads page says 110 deg. but when you click on the link there for data
they list a different degree for that servo [W-150MGR].
It doesn't look like they are proportional reading the data sheet. Like most retract servos they start moving and don't stop until they reach the end of the travel. In this case it looks like the servo travels 125 degrees each time it is instructed to move regardless of the channel on your receiver it is plugged into.
W-150MGR 125-Deg Retract, Metal-Gear
Weight : 16.2g/0.59oz
Torque : 4.8V / 3.9kg-cm / 52oz-in
Travel Angle 125 degrees
Speed : 4.8V/0.19sec/60?
Size(mm) : 26x13x26
Size(inch) : 1.16x0.51x1.02
Motor type : 3-Pole Ferrite
Gear type : Metal