I rarely watch tv, so haven't watched a series/serial for at least a decade. I also do not scroll on my phone. Possibly because of my neural diversity, I find screens as small as a mobile phone screens almost impossible to engage with. The external clutter on the edges of my vision, make concentrating on it difficult.
I would say my attention span is as it has always been, poor in the short term, hyper concentration when the subject engages me.
As for long posts on GN. it is not just a question of length it is also readability. A screen length(on a pc) or more of text, posted as a block without paragraph breaks, punctuation or other use of white space to break the text up, has me elsewhere after half a screen, especially when written in stream of consciousness style. Properly paragraphed, punctuated and written in fairly shortsentences, and I will read to the end.
This is not an unreasonable demand, to ask of people, 'Please make it readable' since at least 95%, if not more, of posters do, long or short, write easily readable posts.