Scheduling the patients that can be seen in one hour at the beginning of each hour instead of every 15 or 20 min during the hour is known as a

time-specified system
wave system
double-booking system
modified wave system
clustering (grouping) system

wave system

Rationale: Time specified system refers to a specific time slot; modified wave system is a staggered wave system; double-booking is scheduling more than one patient for the same time slot; clustering is scheduling patients having similar needs during a common time frame.