When I was teaching High School, we showed the kids that anything we learn, that you refresh within 24 hours will have about an 80% higher retention rate than if you just visit the topic/subject/song one day, and then spend time away from it.
So, if you study a song, or lyric on a monday .... then revisit it on tuesday, you'll remember it much easier than if you wait until thursday to revisit. We proved this to be correct many, many times with our kids.
Study small phrases at a time, and revisit the material the next day and see how it works for you.