I've noticed that a lot of products are touting their "life expectancy" i.e "This should last 6 months" etc. Are these estimates based on age or expected/average exposure to the elements? In other words, would the paint protectant break down over time regardless if the car is a garage queen? I realize that they would break down faster if exposed to the elements, I'm just curious if they maintain their protection longer if properly cared for or if they break down due to time?