Ok PoolDoc, so I should go up to the max recommended 50ppm CYA and expect to see chlorine last longer while initially having to use more to bring FC level not back to 3 but to 5ppm i.e. 10% of CYA level as per your target range earlier in this thread (which also happens to be the max recommended by the National Swimming Pool Foundation CPO Handbook Water Chemistry Guidelines I saw page 44 in the little guide that came with my K2006C).

I then hope the 5% FC bottom target (2.5ppm) is reached at least 2 days later this summer or more than 2 days when the sun is less of a fixture the rest of the year. At today's bleach prices (min 2.2c/oz in my area), there is a strong incentive to make it last as long as possible as it is more expensive than using trichlor tabs (was ~$99 a year though I was not necessarily on top of chlorine levels as I plan to be now and my CYA levels often went through the roof meaning algae).