Good point, Skeeter. And that card is only as good as the diver who takes the time and expends the effort to hone and sharpen their skills, constantly. Even if it's only in a swimming pool, fine. Practice taking the mask off, spitting out the reg, recovering both, removing one's BC underwater, putting it back on, etc.
Next week, my instructor and I are going back to the pool. He's putting the black-out kit on my mask, and then running 50' of rope through my equipment and all around me, so that I can practice self-rescue in low-viz conditions. I want every bit of training I can possibly get. To me, a "C-card" means nothing. It only opens the door to greater training opportunities, and the responsibility to my buddies and to myself to become the very best diver I possibly can.