Guitar Storage

I am fortunate enough to have 8 guitars. Some I play every day, some I play only sometimes, and a few I rarely play. I've heard you should lessen the tension of the strings on guitars that are stored for long periods of time. Is there any truth to this? Are there any precautions I should take with the guitars that I play less? The temp. in my house is pretty much the same year around, but I live in Minnesota and the moisture in the air varies greatly depending on the season...
Thanks

I read somewhere that it's not a good thing to store your gits with lessened tension because you'll be more prone to throw the neck out by having it set with less tension then tuning up back and forth. By having the guitars at regular tension the neck will not have to fluctuate back and forth.
Back when I was living in New Hampshire I made sure the room I had my guitars in had a humidifier in the winter and a dehumidifier for the summer months. They're relatively cheap but get good units.
I live in So. Cal. USA so the weather doesn't require them.
I own seven gits and I try to alternate(five electrics one steel acoustic and one classical).
Any of you all add to this?