I don't think it's ever had much of an effect on Zatanna, Raven, and Dr. Fate's powers. They kind of just make up whatever they need without much in the way of consequence or mass.
Constantine is the one that usually have the "magic brings consequences" dynamic. What is kind of funny, since his magic is way more subtle than anything Dr. Fate or Zatanna usually do.
I’ve always felt that the way magic was depicted in Superhero comics was flawed. It was to open ended. It’s hard to effective challenge a hero when you don’t know what their limits are.
Madame Xanadu had to sacrifice her youth in order to... either a erect really good barrier around a village that I think destroy anything it touches... or a massive fireball one-shotting a group of dinosaurs. I don't remember. It's in Demon Knights.
The Questing Queen in Demon Knights had to sacrifice a baby to gain a prophecy from Hell but of course she's not using her baby.