"Sta-Rite System3 S7M120 Cartridge filter
Sta-Rite MAX-E-PRO 1HP pump"

What causes the problems with the StaRite filters is excess pressure differential across the filter membrane. On a clean filter, with a matched pump, this is never a problem. The water flows easily through the membrane, so the differential across the membrane is not great enough to cause the collapse.

Also, the filters have an enormous surface area -- at least before collapse of the pleats. There is so much surface area, that they may continue to work acceptably in lightly loaded residential pools even if the collapse occurs.

In Arizona . . . filters tend not to get dirty the way they do in damper parts of the country. And, residential pools don't have the dirt load -- especially, the greasy slimy body dirt -- that the commercial pools where I've used those filters have.

So, your filter may work fine, because your dirt load is low enough, so that 1x per year cleaning is enough to prevent any problems. Or, problems may have occurred, but you didn't notice because the filter has enough capacity to keep going anyhow. Or, perhaps Pentair has made some major improvement in the cartridges since I last purchased one.

I have no way of knowing, without seeing detailed photos of your cartridges.

But, I'll stand by my statements. The StaRite System 3 DE filter is an awesome filter. The System 3 sand filter is greatly inferior to the Pentair TR series filters. And, the System 3 cartridge filter is completely unsatisfactory for many pools with loads, circulation rates, and pressures that are completely within the Sta Rite / Pentair specs.

However, the fact that they are unsuited for many listed applications, doesn't mean that they are failing on your pool.

PoolDoc