Sheet-pan cleanup isn't a mystery. None of the usual fixes was built for the whole job.
Parchment paper works once — then it's trash. You cut it, it curls, grease soaks through the edges anyway, and the roll is empty exactly when the cookies are ready.
Foil protects the pan until it tears. One caught corner and drippings weld themselves to the metal. Then it's a soak-overnight, scrub-tomorrow situation.
Flat silicone mats solved the sticking — and ignored the spilling. The food releases beautifully, but the grease slides straight off the edge onto your pan and oven floor. So you bought a mat and still scrubbed the pan.
Greasing the bare pan just moves the problem. More oil means more smoke, more splatter, and a slick brown film that never fully washes off.
It isn't that you're doing it wrong.
Nothing you own is non-stick AND has walls — so every roast costs you a scrubbed pan, a smoky oven, or another sheet of trash.