An additional advantage of valet parking, aside from stacking, is that valets can park cars closer and straighter than some customers may park. This will save them space in the parking lot or garage, and prevent the inconvenience of going to different floors by cramming everything in.
An efficient valet service will implement (or at least prepare) a system to handle the expected number of cars and guests. This may include, but is not limited to, any of the following: designated greeters, stackers, and parkers, a system for marking car locations, and sometimes even a shuttle service for valets at large venues in order to expedite car return times at the end of the event.