Shower and tub clogs are their own animal. Unlike a kitchen line, the enemy here is hair, and hair binds with soap scum and shampoo residue into a dense mat that traps everything behind it. It builds slowly, so the drain gets a little slower each week until you're standing in water.
Stockton's hard water compounds it. Minerals leave scale on the pipe wall, and soap reacts with hard water to form a sticky scum that clings to that scale. The rougher the pipe gets, the faster the next clog forms.
There's also an older-home factor here specifically: many pre-1960 Stockton homes have a drum trap under the tub instead of a modern P-trap. Drum traps collect sludge and are prone to clogging, and they need to be serviced correctly, not just snaked blindly.
