From what the journalist understood an told me, Bolt was able to do more reps last year, so it is more about volume capacity rather than intensity, due to the late comeback to training. In January, Mills was worried? And they are apparently questionning the possibility to double in Berlin.
Before his first 400m a month ago, his last workout was some sub max reps of 120-150m, somethign like 3 or 4 can’t remember.