Yeah I see what you mean - if just one person is left to take the full current, then they likely wouldn't have the control left over their body to detach themselves and they'd slowly fry to death or go into cardiac arrest.
I'm thinking that they can see one another, clearly, even up close. They can see each other suffering.
I had a simpler idea in mind I think - if they break the circuit by getting everyone free, the event supervisors will just execute them. In a carnival-themed way of course! Maybe a roller-coaster which rides fast under tough hanging metal wire that slowly shreds the strapped in girl's faces until the bloody ribbon-headed, twitching bodies pull up at the finish point, and the next to be executed get to see them being dragged out.... Heh. Carnivals.

But anyway... Each girl would surely have had enough at some point and leave one by one, having reached her limit, the one that loves the rest the most staying in the current for the longest, getting fried with more and more intensity as each girl leaves, until suddenly she's the only one left and the others watch her go up in sparks as she bleeds from the nose and bulging eyes which pop with the steam pressure!