One of the best examples is the crumbling exploded masonry planter. In areas where you have a hard freeze during the winter these planters need to be emptied. When it was built short pieces of rebar were placed across the width before the last courses of brick were laid. When it came time to fill it with soil a board was cut to size and placed on the rebar and then the soil was placed on top of the board. One planter I have is 5' in diameter in this case the soil is pulled from the edges and piled in the center.
Obstacles take a beating in the winter.
Leaving them out and exposed to the elements shortens their life span dramatically. If you can't take them down and store them in side for the winter at least cover them. The best stuff I found to use is what marinas us on boats. It's a tough white plastic wrap that you cover the obstacle with and then heat with a propane roofer's torch to shrink it to fit. Another example is not raking up the leaves until spring.