Specifically: bar path (more like the middle and right) and leg drive. Also pinning the scapula back underneath rather than sitting totally flat on the pad.
Also benching twice a week rather than once helped move the needle.
They are good but there are "better" pure quad exercises like hack squats and leg press that don't put so much load on your spine.
I like barbell squats for vibes though sometimes to just lift some heavy ass weight.