Sacred Haven of Debauchery

We actually have the worst situation at ATB (a budget supermarket chain) around 9-10 PM. It's not just because of the influx of people (although that's a factor too, as drunks rush in to stock up before 11 PM), but also because only about half of the cash registers are open at that time, resulting in incredibly long lines. It's actually better to go around 6-7 PM, because there are always a lot of people, but more cash registers are open at that time.
In more upscale supermarkets, where almost all cash registers are always open (and alcohol is more expensive), the situation is the opposite.