Question: The Doctor says he's regenerated half a dozen times since last seeing Sarah Jane. This would mean he last saw her in his fourth regeneration. But surely this is wrong? They last saw each other when The Doctor was in his fifth regeneration, during "The Five Doctors."
Question: When the Doctor says good-bye to Sarah-Jane at the end of the show, it is as if he'll never see her again, yet, he visits her on 'The Sarah Jane Adventures'. Being a time lord, he would know if he'd see her again so why did he say good-bye?
Chosen answer: He doesn't know his own future. She might die or he might regenerate before he sees her again.
Chosen answer: The phrase "half a dozen" is often used as a round number, i.e. "half a dozen" is a little more than "a few." He didn't want to pause and figure it out as it's been a long time in his time line so he just estimated. That said, with the 50th anniversary reveal of the War Doctor, making the 10th Doctor actually the 11th, it's now exactly 6 regenerations since the 5 Doctors, making his statement accurate.
Myridon