Got the following update:
kmod 34-1 -> 34.1-1
lib32-systemd 257.3-1 -> 257.4-1
systemd 257.3-1 -> 257.4-1
systemd-libs 257.3-1 -> 257.4-1
systemd-sysvcompat 257.3-1 -> 257.4-1
Expected a notification to reboot, didn’t get one, week old Mercury install.
I ALWAYS reboot after an update call me old fashioned but just to be safe and to not run into any issues.
I know with Linux it is generally safe to just continue but as i said just to be safe i always reboot.
In recent years, I’ve never seen catastrophe from failing to reboot. Worst thing I’ve seen is kernel module mismatch and the modules won’t load (like a diff filesystem or plugging in a new mouse).
I remember kernel panics and glibc insanity from much earlier years, but I haven’t seen it in a long time.
That said, I typically reboot at a convenient moment after a critical update.
If you get in the habit of rebooting after each update, especially ones that contain core components, then the reboot notifier just becomes unnecessary and annoying. 
I run an update each morning and reboot before starting to use my computer. It’s just a habit I got into and reboots do not interfere with my day since I get it over with before actually starting any work.
I got this behavior from my Window’s days. But yeah I just auto Reboot after any update. I figure its not hurting anything.