"Rock I was simply addressing the "breaks down in three days" part. Not sure what I'm doing differently but it seems to be working."
Might be working where you live, but get back to me in five years...
The issue isn't one, two three, or five freezes during the winter, but PROLONGED freezing, weeks, months, along with intermittent wet--snow melt, rain, etc. That kind of long freeze accompanied by a lot of moisture will turn both kitty litter and other low fired components to mush.
Not sure what kind of freezing you get in SW Wash., but here in Va. --Zone 7--we can get prolonged periods of single digit, even sub zero freezes in Jan. Feb. Soil in pots freezes through by mid-Jan. and can stay that way until mid-March under mulch. I've used lower fired soil components that completely collapsed in the spring following those conditions. Mushy,muddy soil at repotting time means you have a real problem brewing...
Using gravel (or whatever) as a substitute for crushed granite is also unsuitable. Crushed granite used for poultry is not only inert (doesn't dissolve in water --limestone and other stone will), it is STERILE. Both attributes are important. Plain old gravel can contain road salt, chemicals (oil, antifreeze, or whatever has leached into the pile over the years).
Skimping on soil may make some folks feel like they're innovators, but innovation carries a price. They usually pay it along the way at some point...