the general idea is correct, but in practice it works a little differently.
it really depends on what traits you are looking for, and often backcrossing (breeding one of the F1 hybrids to one of the parents) or outcrossing (breeding to a different breed/cross to get or strenghten a particular trait) are also involved, as are inbreeding and linebreeding.
just breeding a particular bloodline for 6 or 7 generations still doesn't mean that after that you have a true-breeding new breed. even in the "real" labradoodles (not just F1 crosses) that have been bred for generations in australia, some traits still aren't established reliably, which is why so far they have not reached their goal of creating a hypoallergenic service dog.
it really depends on what traits you are looking for, and often backcrossing (breeding one of the F1 hybrids to one of the parents) or outcrossing (breeding to a different breed/cross to get or strenghten a particular trait) are also involved, as are inbreeding and linebreeding.
just breeding a particular bloodline for 6 or 7 generations still doesn't mean that after that you have a true-breeding new breed. even in the "real" labradoodles (not just F1 crosses) that have been bred for generations in australia, some traits still aren't established reliably, which is why so far they have not reached their goal of creating a hypoallergenic service dog.