IMO, I don't think it really matters. Because spring tension is basically due to the crystal structure of the spring metal and without large (a few hundred degrees) temperature change, I don't see how a cocked spring will lead to loss in tension.
However, leaving the shutter uncocked does prevent one from taking nice picture of the camera bag.
For Bessa R2/3A users, such as myself, I recommend cocking the shutter after each exposure because the meter cannot be activated with the shutter uncocked. Therefore you can't really meter the scene when you are composing with the shutter uncocked, and you can alway use that darn shutter lock if you don't like pictures of your camera bag. :angel: