Our fall pledge classes were typically between 7 and 10 people, so we never had that problem.
Other sororities on campus had fall pledge class sizes in the 30's. I know of at least one that split the class in half and had 2 sessions of initiation, one a couple of hours after the other.
I can't imagine having half the NMs initiated 2 whole days before the other half - I would hate to be the alphabetically first girl on the Saturday list