I get what BobNC is saying. When I'm in a line, whether at MCD's or the bank or whatever, and if what I'm doing is going to potentially hold up the line significantly then I'm aware of that and I do what I can to mitigate inconveniencing others. If I have a bunch of change to deposit or a large cash or complicated transaction I go inside. If I'm picking up a dozen lunches for the gang, I go inside. At the grocery store I make sure I have 15 items or less before getting in that line. I make sure the clothes I am buying have tags or prices before I get to the register so nobody has to wait for a price check.
If I'm just ordering a big mac and a coke, I'm not thinking about anyone else.
I try to think in terms of how I would feel if I were stuck behind me. It's probably because I worked in retail in my youth and customers tend to suck...so I try not to be that butthead customer some poor cashier has to deal with. Sometimes I am that butthead, but most of the time I'm not.