I've thought about this a lot, too. The conclusion I've come to is that it's a lot like the stock market-- the greatest rewards go to those who focus on a curr

I've thought about this a lot, too. The conclusion I've come to is that it's a lot like the stock market-- the greatest rewards go to those who focus on a currently undervalued variable. Just as buying stocks primarily based on P/E is useless in this day and age, so is counting the number of people in a line. Looking at how much is in their carts is a bit better, but far too many people do that, too. My solution is to focus almost entirely on how competent and quick the cashier appears to be. If and when most other people do that as well, I'll look for another undervalued variable.