Long term it's probably better to get familiar with a few, as each new opening you get comfortable with will grant you a better understanding of the game itself, and not leave you so dependent on memorization when your ignorant opponents go out of book. For a different perspective that answers a question nobody asked: Russian chess schools teach the endgame first, then middle game tactics, then the openings. The aim of this method is for a player studying openings to understand, not just the opening moves, but the ramifications of the opening pawn structure throughout the middle and endgame. Admittedly, studying endgames won't help you if you get clobbered in the opening. But if you learn "backwards" and can just get to a playable middle and endgame, you will find that many players (even advanced ones) are out of their depth as more pieces come off the board.
Opening Repertoire with Black
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What do you think is better: Sticking to one opening with Black which you study and know by heart, or to switch openings from time to time in order to learn about different positions even if your results will most likely suffer?