If I change the desktop background in the interval of every one minute, will it have a impact on battery life? I notice there's even an option for every 5 seconds. Surely, Apple must feel confident in the battery life of the MBP if there is such an option. I like seeing a new image every so often, but don't want to sacrifice too much battery. What do you feel is the best setting? Every 5 minutes? 15 min? 30 min? 1 hour? I'm seriously asking.