That's interesting because the doctor I was speaking with that recommended me to do this method said that they should be fine to stay in forever. I wonder why he said that then?
Also I appreciate your response as always. So if i'm lengthening using LATN my right leg first, by the time my left leg is nailed i'll probably be already all set to walk on the right in most cases correct?
They could stay in forever if you don't mind them there. If you have knee pain,
removing them may help a lot, so keep that in mind. But since you're considering femurs, I guess you'll be fine.
Just an FYI for others, nails like Precice should be removed, since they contain rare metals inside that could cause problems if there's leakage (though odds are very low). If you're in an accident, nail breakage would complicate matters as well.
And your second question: yes, your first leg operated should be in good shape to walk by the time you start the process on your other leg. Lengthen first leg, consolidation + restore gait (3-4 months), then operate on other leg.