file keeper-upper (follower) hack
Decide how full you want to keep the drawer to play comfortably with your files
Deermine if that volume is permanent or if you are you going add or delete files.
If permament, use the space as a depot to store at least two boxes of supplies that you want to keep on hand but don't need to retrieve very often (facial tissues, granola bars, envelopes in their original boxes). When you have used one box, you can still hold up your files but you will be cued to replace the it. If orginal boxes won't work due to size, you can find a cardboard or plastic box or boxes that are just the size you want. If using a box, this is also a good place for some emergency supplies such as an extra set of keys, first aid stuff, birthday candles and balloons, an old pair of glasses, get well and sympathy cards, etc. Pay attention to height of the boxes--I like no taller than 3/4 of the height of the folders.
If you anticipate adding files, the trick is to have several boxes 1" or 2" thick, so that you can remove these and discard or re-locate as you go. A stack of magazines secured all around with tape or string can work too. This also works well for drawers that do not open fully anyway and you have to reach way insdie and peer under to get to the last 4".
If you anticipate deleting folders, look around for something that you readily add in to make up the space. as you go along Reams of paper, more granola bars in their bulk box, magazines taped in a stack, as per above.