I think the question is what is your presence on a social network being defined by? ANd is it appropriate for that network or circle?
Facebook: Unless all your friends are readers and like your work, it's probably not a good idea to keep posting vote messages to that list unless you wish to annoy them over time. Then again, if your entire feed is like that, well then perhaps your circle's culture is going to be tolerant or even favorable of your continued update/vote reminders. Since you have options to make an author page or fan page, those may be more appropriate to use. Sure, the coverage may not be as good (since we know FB plays weird games with visibility) but people are "electing in" to seeing those messages.
Twitter: This is a mixed bag. I'm not just evaluating you on your tweets about your story /reminders to vote. I'm evaluating -everything- you post and whether I want to follow your stuff alongside the 400+ accounts I follow actively.
I don't follow writers on twitter as a rule because many of them, other than telling me they're working on a book, I have no personal interest in their tweets. Do I care about the food they ate? Well, maybe if they're scathingly brilliant in relating it. (I think Avery Monsen of "Your Friends are All Dead" is probably one of those. But YA paranormal fantasy authors? Nah.)
If your entire sum of tweets comes down to "I posted the next chapter, and vote for me" I'm not sure why I need to follow your twitter. I can and will get those updates from Jukepop directly via mail or the app.
However, if that's mixed in with posts of value -- i.e., you're fun to talk to, you're funny, you post /retweet links to helpful content, my focus on you shifts away from "hey you just are here to promote yourself" to "you provide a service" or "you're a good dude."
Not to say that this is how it should be done but consider -- webcomickers often create more than one twitter account. One that is focused solely on their output. So if they're posting a new page, @mycomic posts the news and the link. They might also tweet about recommendations, appearances, or something related to their craft. @personalaccount exists and might retweet @mycomic or duplicate @mycomic content to some degree, but has all the goofy pictures of food they've eaten, their personal rants, or other NON-work related stuff. This, to me, allows me as a twitter user to elect in to the amount of information I want to receive. That said, don't do either if you're not going to monitor them regularly.
Twitter is an investment whether you like it or not. You have to engage with people on it or you will mostly attract bots or other advertisers...
And in case you didn't want to read all the above- I think this article covers it well, although it takes a very corporate brand level approach. It's not wrong to apply it to personal accounts. Many of these points IAW.