I've tried rationing time I spend by setting a timer. No access on shabbos, yom tov, or between 11PM-5:30AM restricts this time sink, but I also do not use this time for other items on my six month list. What I needed to do was set blocks of time that I could use more productively and ban access to social media. My solution, now working well in its third session, has been to just not open FB or Twitter on the days divisible by 4. I've had prototypes of this which have succeeded. On days divisible by 3, I am off from my treadmill sessions to recover from the previous two days. As a result, I rarely miss the scheduled days, short of an injury that sidelines me. Sermo had gotten out of hand, partly as a distraction, partly as an irritant as this physician service lost its intelligensia to the sloganeers and maybe even trolls. I allowed myself access only on days that end in zero. If coincident with shabbos, the usage gap would expand to three weeks. Eventually I didn't miss it and haven't gone on it at all.
Twitter tends to be something like a subway service, always in motion for people to step into and out of the car at their convenience but never really controlling the format. FB is more of a defined community and therefore more alluring. I have noted the size of the community has depleted much as it did on Sermo. Fewer people post regularly, or even sign on regularly, but those who designate this as their forum seem to have increased their entries per capita.
My self-experiment seems useful thus far. I don't miss not being there once replaced by activities from writing to functioning as my home's balaboosta engaged in enhancing my living space. Recreation is more targeted, and FB and Twitter in the process of being redefined as something other than recreation. I seem to be on the right track.