If you continue to flower a plant long after its flowering stage finishes (as determined by its genetics) your plant will most likely go hermi on you and pollinate itself. Even if you don't want to kill the plant will eventually eat itself. This plant is genetically programmed to grow for as long and hard as it can, but once you enter the flowering cycle (12/12) the clock is ticking. The plant will eventually start to eat herself (nutrients from the leaves and such) in order to flower more efficiently, this plants goal is to grow, flower, make seeds then die.

Basically you screw with mother nature and she screws back...in this case she screws her self (quite literally) but you get the point.

You've gotta kill it to get the best bud you can out of it.