If you have just come out of the gym phase and now ready for the track you should not be ready to run anything flat out for at least 6 weeks.
During this General Track Condition phase, start at around 60% and over the 6 weeks gradually progress to 100%.
Only in the last week are you now at 100%. Sticking to JB's program it should be a minimum of 4 days but it depends on the athete. Some might handle 6 days, but you need to have faith the athlete will cope with the intensity.
Once you have emerged from the GTC phase you should be ready for the pre-Comp phase of 60's & 80's trials in Week 7. 50/20/50's are still a staple but maybe once per week.
Bear in mind that by Week 7 it becomes a matter of what suits the particular athlete. Some are more robust than others.
Flying 50's become vitally important between the trials as they enable one to practice technique while serving as a respite between the intensity of the trials.
Btw, we start our Gym General Prep tomorrow.