I'm not aware of any place where carry in condition 3 is legally required. I'd be curious to know where the OP is and what the basis for concluding that carry in condition 3 is legally required is.
And while in the event of a gun grab there may be some theoretical benefit to carrying without a round in the chamber or with an empty chamber in the cylinder of a revolver, IMO the disadvantages more than outweigh any possible advantages. It's certainly nothing that I'd ever consider doing.
The best ways to deal with the gun grab problem are (1) situational awareness; (2) carrying concealed, or if carrying openly using a retention holster; and (3) learning some gun retention techniques.