As W-M said, OTO measurement is a rough estimate, not an accurate measurement of high chlorine levels.

Generally speaking, with CYA level < 50 ppm, treatment needs to be daily or continuous (feeder or SWCG). With CYA from 50 - 100 ppm, it can be every other day. From 100 - 150 ppm, it can be weekly, but you have to raise levels to 15 - 20% of CYA when dosing.

When the pool is running normally, chlorine levels need to be 10% of CYA. Under optimum conditions -- cool water, light load, good filtration -- you may be able to get away with 5%. Where loads are heavy (parties, or small pools), 15% is more appropriate.