The documentation for $.getScript()  function explicit says:
*If you load functions via getScript, make sure to call them after a delay.* [1]

It is suppose that callback functions are always called after a request.
So, it is suppose too that this requeriment is valid for $.get(), $.post, $.getJSON etc?
But documentation doesn't mention the requeriment for other kinds of requests.

Or, am I missing something?

Can someone explain me the needs for this requirement?
What does it means exactly?

[1] http://docs.jquery.com/Ajax/jQuery.getScript#urlcallback