The Phoenix Saga on the Animated XMen from the 90's. Nothing had me glued to the TV like that entire thing. Think it ended up being 2 weeks long (10 episodes). Some nerd who is nerdier than me will correct me.
Became mildly obsessed with UFO documentaries in the 90's too. Had a VHS tape I drew an alien head on and wrote my name on it. Anytime anything related to aliens or UFO's came on, I would record it.
Young me didn't know the difference between SLP and SP on tapes, so I was upset when I was barely able to record 3 hours