First in law without reading full cases?

I'm in my first year of my law degree and to be quite honest, I'm finding it long to get through all the reading on its own, let alone going off and reading full cases/judgments/law reports on Westlaw mentioned in the textbook. Do you really need to read them in full to get a first class mark?

By no means am I trying to slack off and if that's what it takes then I'll do it but I feel it's quite inefficient. What I tend to do is read the material facts in relation to the legal issue, see what was held, and then cherry pick key quotes from judges that forms their legal reasoning (+obiter comments). This is to some extent what I do with articles too.

However I hear a lot that for first class marks, you need very very in depth knowledge of the cases so you should read them in full? So is what I'm doing enough? Or do I need to step up a bit and read the full things?

Thanks