Yes, over and over and over and over and over and over and over. Like drinking, drugs, and sex, responsible social media is a topic of conversation you'll come back to again and again and again. You HAVE to monitor everything and stay on top of it all the time, which it sounds like you are doing. When they get older, you can back off and slowly let them have more privacy.
We didn't allow social media accounts until our kids were 13 (the two oldest are now 16) and had a policy where they couldn't bring their phones to school, had to turn them in at 9 PM (bedtime) and we had full access to everything in their phones and all social media accounts. If they started to get sucked into drama or were otherwise pushing limits - or their friends were and they played along - they lost privileges. We would do things like take away the phone, change the wi-fi password on the computer so they could only use it for typing papers, suspend texting and/or data services and/or change the passwords on their accounts so that they couldn't access them anywhere.
Thankfully, middle school is the worst of it because it's new and by high school, they were using social media for normal communication...posting an interesting or funny picture or video, making arrangements to hang out or practice or study, etc. We let them take their phones to school but will suspend that privilege if they're texting during school hours. My oldest son had a train wreck of a girlfriend this past spring who had sent him several racy Snap Chat pics that he saved screen shots of so when I found those, I took away his phone and iPad for 3-6 months. Apparently at 16 he still needs the threat of parental supervision to behave himself electronically. My SD is also 16 and she is still truly under the impression that we have a key logger on her phone and computer and can see everything she says and does LOL. We told them that when they were 12 or 13 I think and if she still believes it, yay for us! Anyway, my husband will randomly go through her phone and computer but there is never anything inappropriate on it so he now goes months between random checks and really it's only for show at this point.
Stay on top of it and don't be afraid to use consequences to reinforce that this is a privilege and responsibility, not a right. If she wouldn't want her mom and dad to see something, it doesn't belong on social media.