In my last Expert playthrough, to took over 200. 200. Cursed Skulls to drop a Nazar, and still didn't get it. I ended up just giving up on that front. And this was for Ankh Shield, one of my most used accessories.
Yes, while Werewolves and Creature from the Deep are common spawns, their drops aren't. And Golem does drop the Sun Stone, but, and this is absolutely amazing, HE WON'T ALWAYS DROP IT. It's a chance to drop it. You could get 5 Sun Stones in five Golems, or none in 100. It's all up to chance. I've reiterated this twice now.
Depending on your luck, the first Slime you kill could drop a Slime Staff, or literally none could drop it. Depending on your luck, you could get the exact you want from a boss first try, every time, or never get what you want. Does that make it good? Does that make it bad?