The only posts I tend to make to my wall are posts that pertain to everybody and I haven't drawn up an announcement for (and are probably not that important to draw up announcements for). Livestreams, to name one example. But if it's an announcement that I really need everyone to read - cause a lot of subs tend to ignore post notifications, I do the same, there are just so many of them from so many creators - then I'll do an episode announcement paired with a comic of sorts.
There was one creator I got really peeved off with for posting too many announcements though. I won't name names, and I didn't approach her about it or anything, but she was posting announcements so often and hitting the "notify subs" button for every single one, and each post was just random pics of random stuff that I didn't care about lol and so it got annoying really fast to see her filling up my notifications panel with more and more posts of these things. Like ffs that's what I use Facebook for, not Tapastic.
I think some people forget though that you're not actually obligated to hit that notify button. You don't need to hit it to post on your wall, it should only be used to notify subs if it's an important announcement that relates to them. If it's something that doesn't affect your readers or is something that your readers wouldn't be clawing to know, then it's best just to leave it as a regular post without hitting that notify button - or just leaving that kind of stuff to Facebook entirely if it's really irrelevant. Pick your platforms wisely.
I don't know if I'd ever unsub from someone if they posted too many pointless sub announcement posts. Have I gotten real close to doing it? Yes. Hell, I've gotten close to unsubbing from people for having too many series that they didn't put any work into and just kept uploading more without continuing the ones that they started in the first place. I think the only "dignified" unsubs I've made - and I really don't unsub that often without good reason - is for comics that just ended up turning into garbage later on down the road and didn't have the charm or content that it used to have, the content that I subbed to read in the first place. But these kinds of comics are few and far between, thankfully it hasn't happened often enough for me to be hitting the unsubscribe button on a regular basis.
Buuut I'm getting off topic.
TL ; DR if it's not something your readers ABSOLUTELY NEED TO KNOW either pertaining to you or your work then don't hit that notify button, just make it a regular post :U those notifications add up m8