Which is exactly what I’ve said! You’re moving the week that counts from the beginning of the week to start with, to the one at the end of the week.
Once you’ve done that you won’t be able to repeat it until you have a back to back full weekly rest that spans midnight sunday, so the first half will count for the week that’s ending and the second half will count for the coming week, so you’ve now how a weekly rest at the beginning of the week again.
But say the next week you run out on Sunday after having 45 off, you then have a 45 off that crosses midnight Sunday the following week, that is now the only weekly rest in that week, so you’ve just moved the one that counts to the end of the week and lost your chance to do 2 on the bounce ( all if working 5/6 days) you could work Mon, Tue, take 24 off on wed, work Thur, Fri, sat, 24 off on Sunday, then start a full the following week in the last minute of it at the latest. Or even work Thur - Tue, 24 off on wed, but you’d still need a 45 in that week starting no later than the last minute in it