Most Helpful Guy
I live with one of my exes (room mates, 2 years between breakup and reconnecting as friends), but the other (more) serious ex I check her profile every few months on average... She's not very active on social media but it's nice to kinda see what she's up to. We ended on good terms, she's with a guy now and getting married. She seems happy and he appears to take good care of her, so I'm happy for them. I guess nostalgia is what brings me back, a little bit of "What if..." thinking, and just curiosity to see what she's up to.
I wouldn't (and have never) change my privacy settings to prevent an ex from seeing my profile feed. Fortunately my serious relationships have all ended on good terms, I've got nothing to hide.