Conan has always had longer decay timers during holidays such as christmas. The actual timer used to be just 7 days, but they increased it into 10 due to popular demand. I think its fine as is. We dont want stuff of people who have left the game to stick around too long.

All you need to do is log in and look at your base to have the decay timer reset. Stuff that is connected with construction pieces shares a timer.
You can do that once in 10 days, right?
Note that sandstone doesnt get a full timer. I do a round trip of all my constructions once a week. Its fine, just spend a little effort.

ps. You can check the timer with repair hammer. Both your stuff and others. Just in case the server is not being too slow and timer actually resets.