Defending a big blind should not be a huge concern of yours. If you feel like a good player post flop, this could be a huge leak in your game as you are pitting yourself against hands that are worth raising every BB. It simply is not worth it for you, you will get away with it sometimes, but in the long run it is going to be hard to push people off their raised hands. With that being said, it also depends on the position and frequency of the raiser in question. If the raise comes constantly from the button and they consistenly show down marginal hands, then it may be in your interest. You should be playing at a limit where your bankroll can afford to fold the majority of the BB that get raised.