During summer/vacation all the time, feels great. Your feet get stronger too. But for obvious reasons it's not always possible.
BTW flip-flops are not a good alternative for regular shoes or barefooting: http://www.livescience.com/health/080624-bad-flip-flops.html
BTW flip-flops are not a good alternative for regular shoes or barefooting: http://www.livescience.com/health/080624-bad-flip-flops.html