Let's try to really dumb this down...

1) For each X day / PB Day / PR period that gets interrupted, even by 1 minute, by flying the GS, you are owed 1 x PB "day"....it's not a calendar day, it's a 24 hour period.

2) When the rotation ends, add 9 hours and that becomes the start time for your new block of X days / PB days...your new "midnight" if you will. Again, these aren't calendar days...they are 24 hour periods that start at some time that isn't midnight. The PR is how the remaining hours get displayed since we are no longer talking about a full 24 hour period.

3) the ENTIRE block slides right