I mean, if people waiting for OCS already have the Navy/Marine ranks (officer and enlisted) down perfectly, with all pertinent devices, and can recite the articles of the Code of Conduct and General Orders verbatim, and can sing the two service songs (melody and all), and know their Chain of Command perfectly, then sure, go ahead and study those leadership traits. Since I'm assuming nobody has all that stuff 100% yet, I'd highly recommend spending the mental energy on reviewing the aforementioned items. Even if the DI/Chief asks for those traits during 3rd-week RLP—and that's a huge if—the resulting hit won't be the deal breaker. But most likely, they're not going to ask for it. I graduated recently and haven't ever heard of the leadership traits being brought up during RLP. I have seen people take on multiple knowledge hits for missing the crucial items, though.
Only one guy I know came in with ALL his knowledge down cold, and then he got another three weeks to study it even more in H-class with me.
For the record, if you're not familiar with the Star-Spangled Banner, you might think about brushing up on that; that's the last thing I was asked at RLP. I knew it, but my previous roommate didn't. And you call attention before you sing it, just like with the service songs. Same goes for the Navy Hymn, but don't bother memorizing that one. If they ask you for the Navy Hymn, it's because they want you to fail.
All in all, it's about prioritizing (a common theme at OCS). The big stuff is the General Orders, Chain of Command, Code of Conduct, rates/ranks, and the two service songs and the Sailor's Creed. Less urgent are the leadership traits, levels of war, and the breast insignia (focus on yours and your roommate's). If you have the big stuff down and some semblance of familiarity with the rest, you're already ahead of at least 90% of the people going with you.