If you understand a subject, then it means that you have learned it effectively.
In my experience with teaching at university, I have found that the wish of students to understand before learning is actually a great barrier to comprehend a subject.
In order to build intuition on a subject, a student should first try to apply it, play with it (without understanding it) and then understanding will come. But I have yet to witness a student which understand a subject without being able to use/apply the subject.
Take the notion of electric field. You could try to understand it before learning how to use it. Good luck. You are not a fish, so you probably have no sensors of electric field on your skin, and thus you have no prior notion to cling to. I contend that it is virtually impossible. Or you could try to use the concept of electric field to compute forces on charged particle, or compute the electric field created by a charge, or you could build a program that represent the electric field in space. Doing this requires no understanding, just boring substitutions in the definition of the electric field. But doing that forces you to build understanding (its a vector, it changes direction with the sign of the charges, etc, etc)
Another example is understanding how to bike. You could try to understand how balancing on a bike so that it stay upright, understand how moving the handlebar right makes you turn left or, you could just try to bike, and then understand how it works out.
So my advice: don't try to understand. Do, and do again untill you have learned. Not the other way around.