Oblicon: is it normal that I struggled bad with obligations, but do well with contracts??

Book IV Title I (Obligations), I struggled so bad. Failed midterms. But now that we’re in Title II (Contracts), I’m doing a lot better. I get concepts better. Recitations are easier and my prof is more satisfied. Be it, I struggle when Obligation concepts need to be revisited during Contracts statutes, but apart from that, I find it a lot easier.

Is that normal!? Or is it weird??