I have stored a number of pins in my non temperature or climate controlled garage for at least five years now (and vids too) and never had an issue. The only thing I do suggest, pull the backbox glass out of them if they are painted, as you can lose those.

I have yet to have one machine develop planking. I have had a few tiny issues with boards or whatever, but it is equal to or less than what I have with the games in my climate controlled basement.

Then again, I have much more the mindset of an operator than the average collector, which comes from having managed an arcade for a time and seeing this stuff as "equipment", so I get where the paranoia comes from... but I have seen no reason for it so far.