Unless you're a celebrity or massive brand, you can't bank on virality.
There is no guarantee that the content you post on social media (any network/platform) will go viral ... no matter how much time/effort/creativity you put into it.
The exception is if you've got such a massive, engaged following that you are able to post a video of yourself buttering toast and the Daily Mail will write an article about it.
But because we can't all be Kardashians, this means that we have to instead rely more on consistency and frequency than virality.
Make sure you communicate regularly via your social media channels; consistency is replicable, virality is not.
If a post of yours goes viral (and remember that viral to you may just mean a significantly higher than average reach ... it doesn't have to mean 'national news' levels of interest) then treat that as a nice windfall - not something to rely on.