With rep watches, it is impossible to say. Under normal circumstances (a gen watch that has been regularly serviced by a professional watchmaker), a year of idleness should not cause any problems. But much beyond that & the oils begin to dry out, which can cause problems. In either case, I would recommend having any important watches professionally serviced prior to your trip abroad. Then, upon your return, check your other (unserviced) watches to see if the crowns or hands are stiff when you try to rotate them. If so, have the watch serviced before something is damaged.
Bon voyage.