Looks like the manga update notifications come once per day.. But I don't know when exactly it is.. Or maybe I'm wrong..
You have to mark the manga you follow as "Reading or Read" first to activate the Update notification system.
Now you've marked only 5 manga; Raising a Bat just updated 2 days before you marked,
For me the notifications come around 6 - 7 in the evening, so if i open the website in the morning, I'm going to see the update before the notification comes
whenever a manga gets updated i don't get the notification till i see the main page. why is that?