I've read if a few of the How To's that you need remote desktop access on a few of the guides, for example, the write your own buffer overflow scripts. So in a real pen testing enviroment, do you manage to get past the remote desktop access part (gui) or is it easy to gain that sort of access?

I could appriciate a few documentations and programs that can be useful to me.

NOTE: This is not a "Gief meh program that hacks system wit a button click plx kty!!11"
Serious answers please.