I feel like I still need to modify each morning. So let's say today, I'm booked June 14th with check-out on June 21st (the farthest I can select.) Tomorrow, people can book through the 22nd. So don't I need to go on at 8am to make sure no one takes the 22nd?
Maybe I'm confused.
If that's not the case, then when exactly do I need to modify? (Our actual dates we want are June 17th - 23rd. Though I might get an extra day at the beginning and end for a while, in case we need adjust it a bit.)
I think the explanation is like this (assuming no rooms blocked out for maintenance or anything). Let's say for simplicity's sake that there are only 10 of your room type in the system.
Today (July 14, 2023), you book June 14, 2024, check out June 21. As a result of your booking, you have grabbed 1 of the 10 rooms, and no one can grab your specific room for a check in date of June 14, 15, 16, 17, 18, 19, or 20, 2024. The soonest that someone could check into your specific room is June 21 as that is when you'd be checking out.
This means that tomorrow, July 15, 2023, someone could book *a* room for June 15-22, 2024 but they would not be booking your room. In fact, in this example they would be competing for one of the remaining 9 rooms, but the 10th room is still yours because you're still in it as of June 15.
If you did nothing at all with your reservation, then in 7 days, on July 21, 2023, someone could grab your specific room and book it from check in June 21, 2024 all the way to check out June 28, 2024.
However, if at any point before July 21, 2023 you modified your reservation to push it out a few days, then the next time someone could check into your specific room would be the next check out date you have. You could log on on July 20, 2023 and push your dates out all the way to June 20-27, 2024.
So that is why you do not HAVE to modify every single day. As well, this is why you don't have to do your modifications right at 8am est. Of course, you could also modify every day, nothing wrong with that!
EDIT: this is for 11 month bookings, you don't have to modify every day because there is no one that can jump in front of you for that June 22 date for example. If you were booking a resort at 7 months then you do want to modify ASAP and often because an owner could jump in front and grab that room.