Sit into the bottom and let your quads burn down the clock.
Keep your knees tracking over your toes and chest proud. Don't let your weight tip onto your toes.
Parking at parallel keeps your quads under continuous tension with no top of the rep to breathe at, which builds serious positional strength exactly where squats get hard. There's no support behind you either, so you have to own the position rather than lean on it. It earns a place as a leg finisher, a squat depth teacher, and a brutal test of how long your quads can hold a fight.
Start with 20 to 30 seconds and build toward a minute or more. When you can hold a clean minute without your chest collapsing, add time rather than rushing to load.
A wall sit gives your torso a backrest, this doesn't. Holding the free position forces you to balance and stay braced, which carries over far better to actual squatting.
Your weight has drifted onto your toes. Sit your hips back a touch more and think about screwing your feet into the floor, and if ankle mobility is the limiter, elevate your heels slightly while you work on it.
