Obviously when you are running on empty. But otherwise, what is your routine? I pretty much never fill up till Im on empty. I usually fill up at Sams or Costco and the lines there are usually ridiculous, unless you go late in the evening. When Im there, I usually pull into the shortest lane possible regardless of which side the pump is on. I have a 32 gallon tank so fillups are painful, but I hate waiting in line for gas and go only when needed.