While that has worked for me too, I find that negotiating by resignation isn't going to address other issues such as those that bolster the unfair salary. Yes. You got what you wanted, but now they know you played a wildcard and they want you gone on their terms. Or they want to extract the maximum work from you.
> Or they want to extract the maximum work from you
I think that if this strategy works and salary is increased, then the job is burned anyway and I'd be looking for a new one no matter what they say, while pocketing the extra cash for a few months. If management starts to ask for documenting processes or training someone, that's a dead giveway and, ethics aside, the best course of action is (unfortunately) to do bare minimum and focus on job search.
Just to be clear: my point is not that the book taught me to negotiate by resignation :-). The book gave me confidence to negotiate, and I did not even mention resigning as part of the negotiation. Only after the negotiation (a few days later), I chose to resign because of the result of the negotiation (which was therefore a failure).
What the book brought to me confidence: I would have resigned without asking for a raise, saying "well it's time for me to move on" and not "I'm leaving because of the salary". Hence my boss would not have made an offer.
The book also helped me understand how salary negotiation works, and how it is "normal": the recruiter does it all the time, they are used to it, and you may actually look more professional if you know how to talk about compensation than if you just accept whatever they say like a junior.
> but now they know you played a wildcard and they want you gone on their terms. Or they want to extract the maximum work from you.
Not at all, in my case :-).