@i.xvi.mmxvi, it is off, I don't know why. I go by every 4 weeks, & I just use this more or less as an idea.
I understand that part, it just doesn't make sense to me why some months consists of 3 weeks and some consist of 4.
If you are 4 weeks, 3 days, you've completed 4 weeks and are 3 days into your 5th week so therefore you're on your 5th week even though we say 4 weeks 3 days...in other words would be 5th week. 😬 it's a little confusing at first, but when my doctor broke it down to me it made total sense @i.xvi.mmxvi
Lol, I've never gone by that. To me, a month is 4 weeks, and by that chart, not all of the months are 4 weeks.
I feel you lol