US Military Manuals FM, TM, Etc..

I just put a new bookcase in my office and while I was transferring the books I realized I have quite a few Military manuals. Some have glued bindings over stapled pages while others have saddle stapled bindings. (I think that's how you describe these). Did the US only produce one style or did they change printing styles to save money? I know some are reproduction as I bought them when I was young at an Army Navy store that closed years ago and were listed as such. There are many styles out there today for sale. Just looking to see whats correct. TIA.

I looked over my collection and I think the binding depended on the thickness of the manual. But the binding on my early WWII manuals is better than the '44-'45 ones. They probably simplified the binding as the war went on.

Carl