At my house we leave the butter out all the time. Land of Lakes, salted in the one pound tubs. Longest it lasts is three weeks and ive never had a problem with it going rancid. My DW, when we first moved in together was horrified. "You have to refrigerate butter, it says so right on the package!" To wit I told her you dont, watch. She is STILL to this day put off by it. Last week she bought a new butter with a canola oil blend. Supposed to make it spreadable and we can keep it in the fridge. Fail. Not that spreadable, and when she left it out with the other butter the oil seperated from the butter.

-Bill Liptak