Kevins686, no problem with going below 10%, as long as you don't let it die completely. Even then, as long as the meter isn't far out of calibration it won't be an issue. The real problem comes when the meter is far out of calibration and the phone shuts down at 0%, and then won't respond to the charger at all, or the phone will bootloop when attempting to power up.
By the way, you kinda got it a bit backwards... The following is the correct method;
Charge to 100% with power off (this can be started at ANY battery level)
Use normally to 10% with ICS or 15% with Gingerbread (you MUST see the "Low battery" warning pop up at this point or it's not going to have the desired effect)
Charge again to 100% with power off.
The reason for the order above is that the first charge to 100% with power off sets a temporary flag. Then the discharge to 10% (or 15% with Gingerbread) sets a semi-permanent "Low battery" flag. Finally the second charge to 100% now sets a semi-permanent "Fully charged" flag.
Otherwise, you're good to go.
From there, use and charge normally, and repeat the above meter "training" after about every 2 months (Droid RAZR), or 3 months (Droid RAZR MAXX), sooner is OK, later is less desirable.