It's a matter of bro-science.. Ideally you want to achieve higher sustained peek levels,while avoiding dips and fluctuations..So with this being said people seem to schedule their shots E3D, which is not entirely needed as the ester tends to slightly drop just shy of a week. But 3 days is the safe zone to assure higher peek volumes are sustained,with out any dips or fluctuations. I can assure you this, if you utilized the e3d protocol or the e6d, you would never see nor feel a difference.. It all comes down to timing and what people choose to practice.