But from the moment that the script updates and breaks something and the moment he realizes it may be too late for some applications.
For example I host Traccar to track car/vans and in this case some tracks would be lost. Or maybe SyncThing, he may realize days/weeks later that a sync is not working and if he was synching his smartphone pictures with his server and the smartphone is lost/broke/stolen, he may lose days/weeks or even months of pictures.
I wouldn’t trust a script. Use Watchtower or What’s up Docker
I do bond mount data folders of the containers, I do backups, I have a notification system that alerts me if a container is not up, but a container can be up but have problems and, most importantly, I (and I guess a lot of other people) don’t always have time to solve problems. When I a few spare minutes a do a snapshot, I update the containers and if something goes wrong if I have time I troubleshoot it, otherwise I just roll back the snapshot and I’ll have a look at the problem when I’ll have time.