Lever arch files are very useful. They look smart and efficient, but are also very much more bulky than necessary for some purposes. They take up a lot of shelf width, and more vertical shelf space is required than other methods of filing which might be just as suitable.
The purpose of a lever arch file is to keep punched papers in order within protective covers. The papers can be re-ordered, but it is not as easy to do this as it is with a ring binder. If the order is to be strictly observed then the lever arch file is ideal. There are other ~ less bulky ~ methods that do the same job with equal effect. The easiest, cheapest, and most economical is to use treasury tags [124111]. The reason they are not in more popular use is ~ I suspect ~ that they do not look as efficient and professional or business-like ~ papers can splay around.