yeah, no its not true. The plant has the potential to make all of its top 1/2 buds to be equally potent. The key to that is maintaining optimum conditions for the plant to grow and produce to its potential. Topping or training the plant while it is in veg disperses the hormones that drive the branches to push its flower tops high into the air where they have the best opportunity to be pollenated. That is the nature of this plant through evolution. As long as the plant is kept healthy while the training for multiple tops is occurring, the plant will be able to produce equally across itself (given the genetic make up is not weakened for some reason such as poor breeding). The key to the potency of each bud will again depend on the health of the plant and the conditions it is under while the flowering phase occurs.