I’ll pop in to actually defend Stranger Things, and actually recommend watching S3 & S4 ahead of the final season launching at the end of this year!
Comparatively, S2 is an echo of the first season and largely ends up treading water. I believe the term ”Sophomore Slump” to be an apt description.
Conversely, S3 does significantly better in not only upping the stakes, building out the world, and fleshing out the characters.
S4 continues to build upon this, and also successfully binds together a number of plot-points and answering lingering questions, all the while setting the stage for the final series.
100% agree with you on Supernatural though, I struggle to make it much past Season 10 also.