Is Rest Days worth prioritizing?

There is no direct meta-analytic literature under the label "rest days," but the closely related question of optimal resistance-training frequency has been studied extensively: multiple meta-analyses find that training a muscle group roughly twice per week produces greater hypertrophy than once weekly, provided total weekly volume is matched, implying that adequate spacing (i. Weighing that against the numbers, Rest Days is not a priority based on current data — the evidence is only moderate (58/100), and its estimated impact (35/100) is on the lower end too.