I believe the 10-3 rule is sell at 10% gain or 3% loss...
In my case I play a 10% + stop loss and 4 % loss, then sell. This means if the stock drops 4% below my cost I am out of it. The 10% stop loss means that I have a trailing stop for when the stock raises above 10% of the cost (10% gain), I then put a stop loss, if I feel there is more upward growth to happen, otherwise I am out at 10%.
Was a rule given to play and live by to ensure growth and not losses.
Shortime