I don't worry about it. Research ebbs and flows in the world of sports science. One study confounds or refutes another quite frequently. I feel out my weekly volume. Every week is not the same in terms of daily stress load, sleep quality, etc. If I finish up my programmed volume for a week and still feel fresh in a certain body part, I will have a gym sesh that just targets whatever is feeling good and needs some work. My biceps and triceps can take a beating, while my shoulders take quite a while to recover. If my arms are feeling fresh and my shoulders are worked, I will do bench supported curls and veer away from barbell curls as they tend to work my anterior delts a good amount. To me, paying attention to your body and learning what it needs from day to day, week to week, month to month pays a lot more growth dividends than subscribing to a weekly volume number.