I test mine every September, and being I store mine with juice in it, that takes all of 10 minutes. That's the only other time I run them aside from Halloween night. Juice is so super-expensive, I just can't afford it any other time. Though, I do hit Itzaparty the day after Halloween to get my fluid at half price.
last year i had my 3 foggers on the 3 nights that we were open. the very first night it was perfect weather for fog. it was a little cool and there was no wind at all. it was so awesome! the fog slowly made its way through the cemetery then through the fence posts and off into the road... hope nobody gets in an acciden this year! i haven't really had troubles running out of fog juice, i don't think mine take that much. and as for storing them, at first i just left the juice in the foggers, but i got them out to test them out a while ago and one had tipped over causing the juice to come out and get over all of my foggers! luckily they all still worked, just one of my remotes was trashed. now i keep the bottles and pour the juice back it when it's time to put them away.