TV writing logic these days seems to be that each season needs a new gimmick for the arc. But this means that previous arcs start to feel meaningless—and the latest arc too, by extension—because it never adds up; all that time invested in setting up the geriatric thing is just left behind; all the efforts of the siblings one season are just discarded and it's a fresh start the next season. Whereas good writing should always be relating back, tying in the past, making everything you've experienced load-bearing and meaningful, rather than arbitrary.
I can't reply yet because I'm not caught up! But I will come back to this