Coal clamps last about 2-4 weeks off claimed land before decaying.
Timber much sooner, if you harvest day of you will have ~5-10% decayed maybe.
The issue is these days boards are such a valued commodity people will camp out your off claim timber piles untill ready to harvest.
I know of people with dozens and dozens of characters parked all over the map camping out inactive claims/timber piles to check once a day.
Oh and if you're on Roanoke well Russians are big meanies and they will destroy your t-piles even if they aren't ready off claim
