CYA Thank you

As a new comer to pool ownership (4 years) I'm still learning about maintenance, chemistry and such. And until recently have had no serious issues. This year however, through poor maintenance and lack of attention to chemistry over the winter (southern AZ) mustard algae got a good foothold. I used yellow out (two applications) and the pool looked good, but between the high CYA (150) and amount of chlorine required to get back to balance, I decided the best course of action was to drain and refill the pool (small pool, 6.5k gal). And finding Pool Solutions to help better understand and learn re chemistry has helped IMMENSLEY!
There is one issue I don't yet understand though and that is the use of trichlor in both tab and granular. Since both are stabilizer forms, and continuous use increases CYA, how is this beneficial? Once the CYA level is reached the maintenance dose is determined by evaporation and make up water to dilute the CYA concentration, correct? So continuous use of these only increases the CYA level. I know, I know, test and test. Use the right forms of chlorine. Thank you for telling it like it is and giving us real information.

6.5K Gal free form, quartz, Pentair Intelliflo vst, infloor cleaning, Sta-rite System 3 cartridge, Maxetherm 400K BTU heater, K-2006