I replace a lot of rotted wood around windows, garage doors and exterior trim. Much of this can be avoided by maintaining the caulking to these areas. Most home builders only paint the visible portions of trim pieces. The ends and backs of the wood have no protection at all. The caulking done when the home is built keeps water from these unprotected areas. Over time the caulking cracks or falls out and allows water to soak the unprotected wood and starts the rotting process. Left unchecked, this will rot the trim and even the wood and siding behind the trim. Take the time to look at those areas of your home and either do it yourself or have a professional attend to it. Either will be far less expensive than waiting until it is too late.
Bottom line? Replacing caulking is not difficult and is relatively inexpensive. Replacing trim and siding definitely is just the opposite.