How long time does it take for you to file something away?
How long time does it take for you to find something again?

Those are the two important questions in deciding which filing solution is best for you. Keeping both filing and retrieval times as short as possible is important, since the longer it takes to file or retrieve something, the more you will resist doing it.

Under 1 minute is the canonical guideline; I find that around 10 seconds is where my patience ends.