The Gauntlet of Shar was particularly annoying. You know trying to get 4 people to go up the elevator, but only 3 managed to get on and Gale got crushed to death when we tried to go back down to retrieve him. Having to reload and redo the Faith-Leap trial, forgetting to ungroup, dead again. Feels like the game was designed for a player to control 1 PC and 1 Follower at most, because anything beyond that and they're just ambling. Like I'm sure it works fine in Co-Op with a party of 4 being controlled by 2 players and grouped into 2 groups. But for SP controlling 4 it can be quite aggravating.
The exact same elevator thing happened to me. Roughly every few hours of gameplay I'd experience at least a mild annoyance relating to the toilet chain. The elevator thing, party re-arranging themselves to walk into traps, party (& Flaming Sphere) rushing over to me after combat ends and getting hurt by it, party running over fire surfaces, jump fests where some party members don't jump so I switch to them, which results in party members jumping back while I'm jumping forward, etc.
And yeah, the chain system is meant (or is at least less terrible) for a 2-4 person co op experience.