Why Frank was such an important add to the gang
I've been thinking about how and why Sunny has lasted as long as it has without seeming at all stale, and I think a lot of that has to do with Frank.
Let me explain: When we first met Frank back in Season 2, the gang was all in their mid-20s, so their poor behavior was not at all surprising. But adding Frank allowed us to see a much-older version of their atrocity. Without that anchor, we might have judged the gang for not showing any growth over the years, something we might have found too unbelievable to continue to watch. But Frank allows us to see the gang in their final form: unethical, revolting, and always game for Night Crawlers. We know where they're all headed, so we don't actually expect any growth.
Tbh, I would watch them forever at this point.