> I'd have zero clue where I am in the 100+ series I'm tracking

curious question then - do you remember the content of what you were watching? i totally get that you don't know on what episode you are and i used and love Jellyfin myself, but if you're watching 100+ series "at once" i'm starting to wonder if you even remember the last episode of a show if you rotate so heavily, know what i mean? i barely remember an episode after a week, even if i exclusively watch one show. so either my memory is even worse than i thought, or - you have the memory of a savant ;)

It's not like the plots are complex :D

Mostly it's shows that are on hiatus, due to release cycles being completely random nowadays. Or Anime releasing a second season under a whole different show name.

Also shows I've watched 1-2 episodes of and decided it's worth watching, but not now - as there are a limited number of hours in a day.