In a study, one group lifted weights for nine weeks (Continuous resistance training – CRT), while another group lifted for six weeks followed by a three weeks rest (Periodic resistance training - PTR). After the first nine week cycle the groups’ results were similar. The cycle was repeated for nine more weeks, and PTR group’s results were significantly higher.
A quote from the study, Comparison of muscle hypertrophy following 6-month of continuous and periodic strength training:
“Increase in muscle cross-sectional area [of muscle] and strength during the second 3-week detraining/6-week retraining cycle were significantly higher in the PTR group than in the CTR group.”