I knew an old Sussex violin maker/repairer who used to suspend new violins in a specially made vibrating cradle from the ceiling of his workshop. The cradle vibrated at fairly high resonances. Michael (the maker) told me that three weeks of constant vibration was the equivalent of the wood being "played in" for a year. He said it was essential that wooden instruments are played regularly so as to improve the tonal qualities of the vibrating wood.

Guitars I've had made on commission for me have sounded dry on first playing and, by the end of a year or so, start to mellow and "grow" tone.