I dragged the old school Cycleops magnetic trainer out from under the bed, first time in months, and just finished two hours while watching a movie (30 Days of Night). I get bored with training videos so I usually watch a movie or binge watch TV series.
After a warmup I did three sets of seated intervals, 15 minutes recovery, then three sets of standing intervals, and finished with a long easy spin.
My muscles cramp easily and get sore if I'm not careful about a generous warmup and cooldown, so my trainer sessions usually go 90 minutes to 2 hours or more.
Once in awhile I'll do a marathon, either back to back movies or most of a season of whatever TV series I'm trying to catch up on. I watched all of Hannibal, Orphan Black and The Expanse that way -- usually two or three episodes at a time.
I don't often ride longer than two hours outdoors due to an old neck injury. But indoors I can change positions often since I don't need to worry about bike handling or traffic. So I'm more likely to do longer endurance sessions indoors rather than outside. Outdoors, I'll do a few metric centuries a year but my neck won't do full centuries without spasms. Kinda sucks out all the fun.
I usually do indoor sessions in bad weather. I used to ride in rain but I don't trust drivers anymore so I avoid riding in the wet unless I feel like going out after midnight when the streets are empty around here.
In 2018 I was hit by a car, then diagnosed with cancer (surgery got it, no chemo), so for about six months I mostly did indoor trainer spins. It kept me at around 75% so when I was able to resume road riding it was pretty easy to get back up to speed.
Nope, it doesn't really feel like an outdoor ride. I had to regain my instinctive balance and bike handling. Friends who have fancier trainers with rockers and stuff say it's closer to the real deal.