Hello, welcome to our humble Art Forum! Please do enjoy your stay. Now about the topic at hand, being able to have a sizable understanding about things like anatomy and shading have a beneficial role in the way to being a great cartoonist. Being a cartoonist is more than it appears to be at first glance as it has its own set of standards and rules.
When we hear the word "cartoons" we don't usually think of realistic portrayals of objects as most of the time these objects are exaggerated or distorted. In reality, cartoons also follow the rules present in realism. You need to be able to know the rules very well to be able to effectively bend and distort them. Careless distortion of these rules would lead to ineffective drawings that frankly look horrible. So you are quite correct in saying that cartoonists use techniques in realism.
You said that you practice each style on separate days. Although it is an understandable and quite a good regiment to train yourself, I think it would be better to practice both on the same days as if they compliment each other. Such a step would lead to better understanding how both styles work and function as you get to practice these styles side by side. The most important thing is not how much you devote yourself to training yourself, but rather the enjoyment you get while you do these activities. If you do not find enjoyment whilst engaging these activities, all that would be in vain since you won't be able to find the motivation and enthusiasm to push on. Just have fun.