Tourney End Date

Here is my question. The tourney was supposed to end on Fri 23 May at 23:59. Tournaments usually run for 4 weeks and this end time would have been just a couple off minutes short of the 4 weeks. The end date was changed yesterday and a day added. The tourney is 22 days 8 hrs old as I write, this can be seen by the time squares have been occupied, yet the rankings are only up to Day 20. So today when the rankings are posted they will be for Day 21 where they should be for Day 22. Just what has got the Devs confused. Where did they lose a day. In order for this to be a 4 week tourney or 28 days it would appear that there should be 5 days 16 hrs left. Could the Devs please clarify this for me. I trust my reasoning to be correct but there again I am a flawed human and thus prone to err.