Whatever you choose dont wait until the day of departure to ask your guests what time they depart or remind them of departure time. Thats not being proactive. It creates confrontation and provides the guests few options. Always do your best to get departure information details BEFORE the guest arrives and BEFORE the day of checkout. If the guest hasn't made it obvious they are in the middle of packing up then giving them an hour notice isn't going to do it. Furthermore, they are likely going to be sleep when you message them.
I always ask before their arrival of their departure time. If I don't see or hear that they are in the middle of packing the morning of check out then I knock on the door or ring them and see whats going on. This is a rare occurence and only happened once. Come to find out they were drunk, hungover and pretty much dead to the world. Once I understand the circumstances then I can move forward. I messaged another guest about their check out plans and he was surprised my check out time was 11. Not sure what time he thought check out was but he eventually arrived back to my house packed up his things and we said our good byes.
I don't offer back to back reservations if I'm not off work that day and although it affects my occupancy it provides the guests and me a little wiggle room.