But when you really reach that level, you need little training.
From my personal experiencees, when I took my 1st TOEFL test in college, I got 603 after tons of Training. On the contrary, when I took TOEFL last year in Toronto, I got 273 ( =643 in paper test ) with only 4 days of preparation.
I don't wanna say TOEFL training is not important. But if you live in a English enviroment and keep practice, training is much less significant than before.