Paul Giroux writes:

On another matter I would be curious to hear your opinion on the
suggested practice by the industry of superchlorinating a pool every
week. Actually the interval varies depending on who you talk to. I am
under the impression that if you maintain your ORP at 650 then this is
not needed, upsetting the pool industry because you're not buying
these little bags of 75% cal hypo at 3 times the price of the 70%
stuff in your big bucket.

Superchlorination is the best way to clean up accumulated problems.
Residential pools tend to accumulate problems, because they tend to
fall below minimum sanitation at a moment's neglect. Moreover, with
the CYA scheme, there's hardly enough chlorine to keep you from getting
sick, and not enough to keep the pool clean, thus the need for routine
superchlorination.