The patch updater used to automatically run in 17, but does not anymore in 18.0, I have repeatedly examined the settings there and found no faulty setting - to my knowledge - so I made it a habit to manually launch the searching procedure once or twice a week. Which was okay.
The update for 18.1 however does not show up in the ordinary way like other patches, you have to manually check for a menu entry that you usually would not look at, so if you do not know that there is a OS update out, like I did not know, you easily could miss it.
I suspect that the patch updater had a problem in 18. Could not make it running automatically.
18.1 did no damage at all to installed software and files. Even system tasks running in the background and manually added by me were not affected. Thats what I call smooth OS updating. And fast!
(Even Google Earth, which is a vulnerable thing under Linux and has given me repeated headaches now, retained its stability and functionality that I got since I last time installed it. The version installed by Synaptic does not work, use the Google site-package and do it man ually, then it works - and only then).