Office/School/Home: When you use folder, do you prefer fasteners or sliding?

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In some cases that i use folders i used to prefer sliding however i realize that fasteners were much better. Its embarrassing too how i realized it. Which also lead me to liking envelops more. This is what happened: I was in a hurry, practically half-running, late for an appointment with all my filed at hand "in several sliding folders" when swoooooosh!!!!! I slipped!!!!! Everything few in the air all my filed which i chronologically did arranged... though a lot of the passerby helped pick it up, i was all red... from that time on i prefer fasteners and envelops. How about you? what do you use more?