> 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.