Tried to use servo.writeMicroseconds to get more accurate control for the servo. It looks however that there is a threshold built into the library and not each value gets sent to the servo. Could not find the source code to verify my observation.

You can find the location of a library by opening one of the examples of the library from File > Examples and then Sketch > Show Sketch Folder. This will open the example folder which is inside of the library folder.