I saw a review on IMDB saying it could have been ten minutes, and I can't help wondering whether that person has watched any of the rest of the show until this point. The whole thing has been glacially slow, even if it doesn't really feel that way.
And by reserving an entire episode just for Harmony's back story, they didn't have to interrupt the main timeline.
Overall, I am fascinated by how they manage to make the pace both slow and suspenseful at the same time. But in this episode, the suspense was completely missing for me, and the revelations felt very on the nose.
Funnily enough it's the opposite for me, usually I'm gripped by every episode, but this one I ended up doing other things after 15 minutes, something I haven't done with any episode of Sererance yet.
I have watched all severance episodes, and some many times. This was undeniably the worse episode. The events that took place could easily have been a 10 minute side story from a different episode, but instead they made it an entire episode.
Yes, other episodes have been glacially slow, but in those we gain lots of insight into the universe, or at least we spend time with the characters we care about.