Do you Use an Oven Liner?
I've always put a cheap aluminum oven liner on the floor, under the element.
I notice the new ones say to put on the lowest rack.
Is there a reason why it shouldn't be on the floor? Do you notice an uneven oven temp using them?
For things that I know will spill over....scalloped potatoes etc, I always set the dish on a cookie sheet, but pizzas drip onto the oven tray, so I don't want to *not* use one.