I’ve tried a little of this in the past – It is always weird “talking to myself.” Scratching my head, saying “uh” a lot – I’ll give myself a “6 out of 10” with a LOT of room to improve …
Just me talking for 20 minutes – mostly about Buster Keaton’s “One Week” silent movie.
When the “projector” came out – movies increased in length. There were probably obvious “increments” – e.g. from 30 second novelty shorts to 5-7 minutes longer form, then 20 minute features were very popular, eventually the “2 hour runtime” became “normal”.
There does seem to be something “magical” about the 25-30 minute length, you can get a lot of story into 25 minutes without having to introduce plot complications.
Modern “sit-coms” tend towards that shorter length (since the goal is “comedy” not “pathos”) while “modern drama” tends to be in the 45-60 minute length.
Still add a few plot complications and you could easily make that 40 minute “sit-com” into an hour, or strip out the secondary plot and that “hour long drama” could fit into 25 minutes …
Something about “human attention span length” also applies – but you tend to see a “three act structure” in most modern storytelling forms – that might be a subject for a phd dissertation (requiring some real research to back it up) or just a random observation after spending some time commenting on a silent film from 1920 …
https://rumble.com/vjuw3d-commentary-on-buster-keatons-one-week.html