General conditioning effect: To get this benefit you must take short rest intervals between each exercise. (muscle-fitness-training.com)
You will discover that sticking to a set rest interval between sets throughout the entire workout will ultimately be what gets results. (resistancebandtraining.com)
Other details: longer rest intervals of 2 - 3 minutes in between sets are required during heavy lifting phases. (stomachfatisugly.net)