Back in August, when I made the changeover to the new system, I had the following occur:
I had 3 accounts, 6 months plan (or is it really 180 days?), due the first week (+/- a few days or so) of October, November & December.
The December one had no noticeable change (MIGHT have gotten 2 weeks, after falling to the end of November, but not sure)
The November one got 2 weeks added to it, moving it to the 20th.
The October one got SIX weeks added to it, to where it ended the SAME DAY in November.
My balanced "pay one account in 6 months of the year, when bills are lowest" plan got royally botched by what free time I got, as it pushed all 3 accounts to be due in a period less than a month (closer to 3 weeks, in fact). My finances are still messed up from that, as the bank account was shared by my mother and she assumed I'd already paid the UO stuff based on teh days marked on our calendar.
I don't know if those were the "2 free weeks" I got (actually added up to 8 total weeks for 2 accounts), or just an artifact of the changes to the system, but it was a pain. Who would have thought free time would have a negative impact.