[jessriedel]

Yes. The bottleneck is the total throughput of the cashiers. Now, better deployment of cashiers can help. If you have N people come into your store, you're going to have to check them all out at some point. The problem is that if you always have enough cashiers to help people as soon as they are ready, you'll be paying cashiers to stand around during lulls. Stores try to avoid this by moving cashiers to other jobs when there's a lull, but this only helps for fluctuations with timescales long compared to the time it takes to start and finish a job.

hrabago's point is important, but it certainly doesn't justify the linkbait title. A single line will decrease the variance of the wait time. Since the customer's impression of the wait time is very non-linear, this might significantly reduce customer unhappiness. But that isn't some brilliant insight into the process of handling customers faster.