Presentation folders are not necessary for every project. Many proposals or submissions stand on their own without the need for presentation folders. However, it is not hard to know when you should use them and when you should, you really should.
The first impression received is often due to presentation folders. In times when your work will be lumped in with many other pieces of work, using presentation folders will identify your work as your own. It is important in these situations to set yourself apart and presentation folders are a great way to do it.
Other times to use presentation folders are for promotional efforts. If you are preparing marketing materials for general distribution or for a trade show, package your information in presentation folders. This will allow you to present more information than you would otherwise be able. Bi-fold or tri-fold presentation folders can let you include much more about your company and your services which will undoubtedly lead to more interest.
It isn't difficult to identify the right scenarios to use presentation folders. Make sure you use them to your advantage when you can and not to waste on them when they are not necessary.