See, it's not supposed to work like that.
Seriously, with social media - especially Twitter, Face Book and Instagram - consistency is key. Even if you are a huge mega-star, some of your million followers will most certainly lose interest if your only goal in using your Instagram account is to tell them when your next tour kicks off and when your new movie is available on Blue ray. Yawn...
As a publicist, I tell my clients the exact same thing: don't neglect your social media. Ever. Yes, I know you're busy, but - especially when there are so many great (and free!) programs that allow one post to hit all your accounts at once and even the convenience of scheduling posts hours, days or weeks in advance - there's really no excuse. Heck ya got me and Hootsuite, baby!
Your posts could be as relevant to the thing you do as you wish - or not at all. Your minute-long grocery store video may have nothing to do with your most recent project, but it does show you are human and relatable. Blending that on social media with "the artist at work" type of stuff can be a great mix for a fan base excited to learn more about you and your creative process. That's not to say they want to see you flossing your teeth or folding your laundry, however. There's balance to be found, for sure - but you won't find it if you post a countdown to your book tour kick-off and nothing else until the tour is almost over.
Start small if you must - posting a quick song lyric or photo of your computer keyboard or even a screen shot of the music you listen to while you sculpt once a week or so - but start and remain as consistent as you can.
Don't let weeks or months go by between posts. Yeah, stop that already.