I always take 2 watches on trips. One a beater for casual and the other a Sub for those dinners or lunches at a nice restaurant. I use a single Watchpod for the watch I’m not wearing and that stays in my carryon or backpack.

They get carried in a watch roll or similar as suitable.

And always carried in hand luggage - anything valuable or delicate should always be carried with you to ensure its safety. Packing it in hold baggage means it is out of your sight and in the care of others. 99% of the time there won’t be a problem, but your bags will be thrown around by the handlers, and there is always a chance your bags don’t arrive on the same plane that you do or just don’t make it at all, and I certainly don’t want to risk losing my watches or other items like computers.