It depends on the individual pool, location, weather patterns, etc. If someone lives in a location with a short swim season and they drain a considerable amount of water from their pool for winterization then they may get away with a good bit of trichlor use. Or perhaps they have a longer swim season, but get a lot of rainfall that dilutes the CYA thanks to overflow. Alternatively there are also those that will think all the high CYA side effects are normal, they start off the season with manageable CYA thanks to winter rain fall, winterization draining, etc. by mid July they start having algae issues, so they add some more of their weekly shock (which we can hope is Cal-Hypo powder), they continue fighting such things blaming it on the weather, the way pools are, etc. until the end of the swim season, often nuking the pool with what we would see as insanely high FC levels to combat the ever rising CYA, and if they get lucky they make it through until winter, and the cycle repeats until something happens and it all comes crashing down.