In my opinion even two of three days is too long. Overall degradation of the battery begins as soon as you charge them up from storage so the least time possible leaving them fully charged is my aim. When I know I'm gonna be flying I charge up batteries no earlier than the evening before the expected flight and if that flight is gonna be in the afternoon I charge them that morning. For me, then, around 18 hours is the absolute maximum time I have my batteries at full charge. Ideally it better to charge batteries with as little time possible between the charge and flight but leaving enough time to let the batteries settle down.
For example, I'm expecting to do a job next Tuesday morning that will require 3 batteries. I will check the weather conditions for Tuesday at around 6PM Monday and if it looks good I will begin charging two batteries up at 7PM Monday evening and the third battery Tuesday morning while I'm having my breakfast. Note that the actual job will only require two batteries, the third as a spare, just in case, which will be either run down in the field after the main job or will be discharged to storage if I don't get the opportunity to deplete it in flight.