I haven't really had group therapy, but when I was in a residential facility we had 'goal discussions' (weird translation, I know) every afternoon after tea/coffee. Basically everyone had a 'goal of the week'. This could be anything from 'getting out of bed on time in the morning', 'smiling at myself in the mirror five times a day', 'filling in charts whenever I experience a strong emotion', or 'using my coping/safety plan when I experience anxiety'.
Everyone was always supportive. The group itself was always mostly supportive, except on What'sApp - that was about as unsupportive as could be. Extreme descriptions of self harm, etc. People seemed to be proud of how messedup they acted. What didn't help was that people who had been in the facility remained in the group chat even after they'd been discharged. I quit the what'sappgroup after a few started to demean a new client who wasn't in the group chat. (I also emailed one of the nurses that that was happening)