No strings on a classical guitar can damage the instrument. Is this a myth?

[Pete]

Is it true that if you take off all the strings on a classical guitar and leave it like that without any strings, that it could damage the guitar somehow? Not sure how long, but some say never take them all off even when restringing. To just change one string after the other. Is this nonsense? What about a full day or a week without strings?

My made up assumption for this would be that the wood gets used to the string tension after yrs of having strings on 24/7 and when you take them off and leave the guitar without tension that the wood maybe gets a rest or relaxes maybe and that movement may create issues. That is just my made up assumption.

Anyone can elaborate on this and whether it is true or not, how long without strings is bad? 1 day, a couple hrs. or altogether this is nonsense and I can rest my guitar in it's case unstrung for years and nothing will happen?

Must sound silly, but there are a ton of people who think this is the case, so I wanted to know if this is true or not and to what degree.

Thanks for you feedback

[Mark Pollock]

The reason not to take all the strings off a guitar is if you have a bridge or saddle that will fall off when they are removed. Other than that, the only likely harm would be ennui.

[Russell Vance]

I suppose that if the guitar was predisposed to back bow the neck through environmentals working with the neck wood/heel joint in question you may assume that the tension provided by the strings to keep the neck tending towards relief over time is beneficial to the guitar remaining playable.  If the guitar is soundly made this will generally not be an issue, particularly if the instrument has normalised to the environment over time, but in some cases it will be(come) a problem.  

Taking the strings off for a day or a week or longer in a controlled environment won't do anything technically. 

The technical aspects of what wood does wrt temperature humidity and tension is not a simple subject.   Properly conditioned good quality wood does not rest or sleep and only relaxes if you give it a six-pack.

Rusty.  

[Hesh Breakstone]

No +3 except of course if your friends are a little...... unpredictable.....

Poor Guitar....