A: The short answer is: As long as they need to.
There is no set time limit on how long or short deliberations can take. The judge will allow the jury to take as much time as they need. If that means taking three or four days or a week or even longer to reach a conclusion, they can do that. There are instances where juries cannot reach a decision because of infighting, disputes occurring during deliberation and notes sent to the court reflect an impasse. There have been many instances where judges will remind a jury of their civic obligation to reach a decision and compel the jury to return back to the jury room to continue to work it out.