They are called sketches because the Arduino was explicitly designed for Artists to use.

 

Everybody else in the world uses "sketch" as either the term for a rough drawing or a drawing without accurate details. Thus the use of the term to denote a program listing comes across as an effort at obfuscation. Using a wrong word so as to confuse others. And when the word "sketchy" is used it is intended to mean something lacking in details.
It all comes across as similar to Timothy Leary after his first hundred LSD uses. Not speaking in words intending the same meaning as we normally use them.

I don't speak for the whole world, but the O.E.D. does for those who speak English. While there is certainly an element of lacking details in the term "sketch," according to that authority, a simple program using Arduino's version of C certainly qualifies:

Source: OE.D. (examples deleted)
1. A rough or unfinished drawing or painting, often made to assist in making a more finished picture.
1.1 A brief written or spoken account or description, giving only basic details.
1.2 A rough or unfinished version of any creative work.

In my experience, "sketch" is used just as often to describe writing as drawing.

 

My interpretation of that is that the servo is powered directly from the power source. Signal is D9, and that requires almost no current. So no problem, except as mentioned in post # 3 , there could be ground noise. Be sure the arduino has its power and ground properly decoupled.

How much power/current your supply can provide, depends on the supply, not the arduino. A lithium battery will probably not be a problem. A USB2 port may be a problem.

I had never considered that there was a reference to an RC servo. That does alter the whole question a bit. ALL of the servo systems I have used have been of a more industrial nature, with a few of them being in the electro-hydraulic form. So those little RC servo packages that require a variable duty cycle command signal are really a very special case of servo-mechanism.

 

There are millions and millions of them, even companies specializing in making RC specific servos, I don't think you can call that a special case.