My wife has run into two people this week that store their butter on the counter or in the cupboard to keep the butter soft for spreading. I have read a few articles and the ones that say it is safe to do mention that salted butter is the best choice because of the salt acting like a preservative. They also suggest that you can do this for just a few days before the butter goes rancid but no article gives definitive amounts of time. Is this practice done widely? Thanks.