I wash my oven out every 4-6 weeks, the shelves are soaked in the sink with hot soapy water while I wash out the shell of the oven, then I scrub the shelves and side shelves with a wire scourer, they are a godsend they shift the stubborn grease quickly.If you keep up to it it saves you a lot of time and mess later on..Wiping the shelves down when the oven has cooled down a after cooking cuts down on the build up of grease in between times. I also line my grill-pan with foil so I can throw the foil away after using it and wipe the grill-pan out scrubbing the rack with a scourer if necessary.