There is another variable in this equation - closing the loop between on and off website marketing, as well as between different social media channels. In my experience, a social media strategy is only effective when it's executed in tandem with all other channels, as well as across all of the social media channels.
As an example, if you are making a certain post on Facebook, what are you doing on Insta, Twitter, Tumblr, Snap, etc...? And additionally, how are you tying these posts with the messaging on the website itself? And finally, how are you connecting these two sets of efforts with any other off site marketing/advertising you are involved with (such as Google Adwords, Pinterest ads, etc...).
I think that a winning social media strategy would consider all of these variables. Curious what others think.