I'll flex test mine when I pull them out of the target usually. Once you get into that habit, it really doesn't take any significant time or effort.

Any time I might have hit another arrow or someone might have hit mine on a 3D course, I give them an extra good check and flex test in three or four directions.

Next time you go to pull your arrows out of the target, think about that picture and see if you don't start checking yours everytime too!