In GTD, David Allen recommends letter rather than legal size file folders.

However, what do people recommend regarding the folder tabs and why?

Some folders have the precut tabs for labelling, either 3 or five in a series. Some don't have a precut tab but just have a "lip" at the top that extends the entire back of the folder up about a half inch for labeling.

I've always struggled with this, because if you use the precut labels, what system is best? A - L on the right tabs, M - Z on the Middle Tabs, etc? Problem is when you add files, whatever organization system you use gets mixed up....

thanks!
Publius