I've heard different BBers say different things. Some guys are hyper and don't like to hang and wait. Some have good cardio and trained for many years and like to get it done. Others spend time, a lot of time in the gym. From pubmed;AIM:
Between-set rest intervals (RI) may be determined using exercise-recovery-ratio (ERR) or fixed periods. The study investigated the influence of different ERR and fixed RI on the training volume in sessions aiming for hypertrophy with upper-body exercises recruiting different muscle mass (bench press-BP and triceps extension-TE).
Determining between-set RI based on ERR instead of using fixed intervals does not enable more work to be done in multiple-set/high intensity resistance training sessions.