Basically, face amount isn't all that important. The speed with which most EE bonds increase in value is based on interest rates during the time you hold your bond. If you hold your bond long enough, its redemption value will reach and exceed its face value. The maximum time that it will take for your bond to reach its face value depends on the rules in effect when the bond was issued. The actual time that it will take for your bond to reach its face value can't be predicted since, in most instances, the time depends on interest rates.
Final maturity is really what's important.
This is the point after which your bond will no longer earn interest or increase in value. Check your savings bond inventory from time to time and promptly cash in or exchange all bonds that are no longer earning interest. If you don't redeem bonds that have reached their final maturity, you're letting us continue to keep your money without paying you for the privilege. While at one level we appreciate the patriotic gesture, we really want you to earn interest on the money you have graciously lent your government. See When Bonds Stop Earning Interest to find out when your bonds will reach final maturity and stop earning interest.