Both are okay.
You are not expected to gain an intimate understanding of every single formula you'll ever use. Sometimes we use proofs to convince ourselves they're right, and then just memorize the damn thing by applying it over and over.
Its better if you can get an intuitive understanding of it. Like if I told you I wanted you to complete a picture of a square, and I draw 3 of the sides, you could draw the 4th side, right? Intuitively. You could see it before you even drew it. You could feel that its right.
Its great to have that kind of intuitive understanding. But its just not possible sometimes. I'm sure there are maths that people do in high dimensions that we just can't get that kind of feel for. And that's okay.
That's how I describe the difference anyway. Sometimes the logic just makes perfect sense to you and you can intuitively feel something. Sometimes, you can't.