I have two refrigerators. One in the garage and the other obviously in the kitchen. The one in the garage probably needs cleaning once a year since all it has is extra gallons of milk, juice bottles, juice boxes, extra ricotta cheese containers, sour cream containers, cream cheese and butter. I do sometimes store fruits there if I have in excess but never regular food. This keeps it pretty clean.
The one in the kitchen needs cleaning every couple of months. But, I do clean it inside out twice sometimes thrice a year. That means the entire contents are removed, the refrigerator compartments, shelves, bins are removed and washed. I used to wash the partitions, bins in the utility tub in the laundry room since that can hold big pieces. But, there is one shelf in my refrigerator which is too big for my utility tub too. Plus, when I am trying to rinse, there is water spillage around and all the mess. So, this time, I took my refrigerator parts outside and hosed them down. It was so fast that I probably will keep on doing it every other month now.
This is how I do my refrigerator cleaning.
Wait till your vegetable supply is almost over. It gets easier. Empty all the contents and remove all removable parts of the refrigerator.
Wash them with water. You don't really need soap unless it is a mess. Water and vinegar solution is very good to clean the refrigerator. I use 10 parts of water to 1 part distilled white vinegar. Rinse the parts with water well and then rub them with this solution. I actually used my steam cleaner to disinfect and clean the parts.
Dry them (fun for the kids to do. I gave both my kids couple of paper towels and they went to work). You don't have to dry them completely since inside the refrigerator they will dry a bit because of air circulation.
Wipe down the inside walls and floor of the refrigerator clean.
Put all the parts back into their place.
I line the entire refrigerator except where the vent from freezer is present with paper towels. It extends the time when I have to clean it again by absorbing the spillage.
Keep the things back in the refrigerator.
The way I keep stuff is by moving stuff that I hardly use to the back. Things that I reach very often are always in the front. Adjust the heights of the shelves so that you can utilize the space to its maximum extent.
Here are some pictures. Refrigerator fresh out of bath..