It’s a heavily debated issue on how often you should train a muscle group. A new study published in July 2022 in the Scandinavian Journal of Medicine & Science in Sports claims that a small amount of daily activity can be more beneficial than a single high volume session of exercise.
The four-week study split 36 untrained college students (24 males and 12 females) into three groups to measure the change in muscle strength and muscle thickness while performing max effort eccentric bicep curls. Group A performed one set of six reps each week, which unsurprisingly did not show any changes in muscle strength and muscle size. Group B performed one set of thirty reps each week which resulted in a six percent increase in muscle size but no additional muscular strength. Group C performed six reps five times per week which resulted in both a ten percent increase in strength and a similar increase in muscle size to Group B.
Many people have a muscle group that simply refuses to grow. For me, it has always been my chest. Once I switched from a single high volume day to training three times a week incorporating a day of power, volume, and accessories, my pecs have greatly developed. So if your single high volume day is not working, why not try hitting your weak areas multiple times per week. A higher frequency training program will help you develop better form,deepen your mind-muscle connection, increase your overall training volume, and won’t allow one bad day to ruin your gains for the week.
As a final note, this study is not conclusive and there are many other studies that contradict this result. For example, a 2019 paper by Brad Jon Schoenfeld et al. J Sports Sci. did a comprehensive meta-analysis of 25 studies involving training frequency. They concluded that resistance training frequency does not meaningfully impact muscle hypertrophy when volume is equated. Therefore you can choose a weekly frequency per muscle group based on personal preference.