Real true breeding is an art. A true breeder, once they know what strains they want to cross, will begin with as many plants as possible and cross males and females of each plant with males and females of each other type of plant, making crosses with a male and a female and a female and a male of each phenotype with all other phenotypes. They search for which plants pass on traits they want to be passed on while not passing on unwanted traits.
Once they find what they believe to be the best, then they go about stabilizing the cross. Once stabilized, if nothing is lost in the process that might require another cross to try to put back what was lost and then stabilize again, only then is their job complete.
Breeding sounds cool and the gang to people but it just ends up adding more unstable or only partially stable mutts to the world that can end up later mucking up another strain when someone makes the mistake of using it in another cross.
I wish there were fewer pollen chuckers in the world cranking out mutts.