Look deeply into any restaurant running at peak efficiency, and you'll notice at once that every team member has their own role that perfectly complements everyone else. Hosts, servers, and food runners seamlessly manage the clientele FOH, while cooks, preppers, bussers and dishwashers make sure that everything runs smoothly in the back, and at the same time, the management team provides an effortless conduit.
Everything runs like clockwork; orders are taken, placed, made, delivered, and cleaned up in a flawless process, and when bad things do happen, like a broken dish or a returned plate, anyone can jump in and pick up the slack.
System quality really comes down to the experience and skill of each of the front-line team members, along with the leadership of the management group. When an establishment is fully-staffed and capable, managers can take steps to enhance performance and customer experience, such as offering a specialty drink service during a busy meal shift, or bringing in sales pros to roam the floor and up-sell clients.
In this sort of environment, the added customer service is obvious to everyone involved and directly corresponds not only to traffic, but also to a larger ticket. A well-staffed and managed operation is going to have the capacity to go above and beyond to provide better service and make diners' experiences memorable, and they're going to be well-rewarded for it in higher sales and extended loyalty.
On the other hand, when a team member leaves the company and needs to be replaced by someone new, the whole system degrades a notch. One lost person automatically translates to two out of place, because a manager will need to task a senior position to perform mentorship and training. Lose another employee and now you have two senior members training two newbies and things really start to slide.
With four staff members now out of commission, everyone else needs to work faster to pick-up the slack, and before long, the tables are overflowing with dirty dishes, and there's a line-up at the cash register. Service times become untenable and orders start to lapse. New customers waiting to be seated give up and walk out. Eventually, food quality starts to suffer which triggers a vicious circle, as disgruntled customers start sending plates back to the already overwhelmed kitchen, and nothing good ensues thereafter.