The Target Effect

It seems that everytime I head to the check-out at Target, 80% of the customers in the store are standing around in three lines, staring at each other with frustrated looks.  

Am I the only one who consistently experiences this?

The questions that come to mind...
-- why have 24 registers, but only open 3?
-- is there a gravitational pull that causes all of us to check out at the same time?
--should Target have a couple of registers reserved for use by RedCard holders?