Drawing the same thing over again is the easy part. The hard part is drawing something different. We tend to get stuck in our conventions. Once you figure out how to draw something, all you have to do is exactly that, again. How did you draw it the first time? That's easy, you were there, you can retrace your steps. You might not be aware of how you drew it, but that gives you a good opportunity to figure it out. Learn about yourself, and why you draw the way you do.
When you're talking about an exact replica, you'll need to use a grid system. There's no avoiding that. But exact replicas are not necessary for neither animation nor graphic novels. It's not even necessary for the proportions to be the same. Unless you want it to be. Or maybe the writer wants it to be, or the publisher wants it to be. You get to decide the answers to these questions.
When you start drawing you will find out that drawing the same thing over and over again is easy. Because naturally that's how our brain works. Simple patterns and formulas. Obviously it will be noticeably different. But for exact replicas it would be worth it to invest in digital media, so you can copy and paste and not have to deal with spending time making grids.
You can also use a projector to project onto the paper and then trace the projection. That's a perfectly acceptable method that professional artists use all the time.