Worst one I ever had was a guy who was sat on the pad at an outpost, in Open, for two days.
Seriously, 40-odd hours just sat there.
I forget the exact circumstances but I was trying to help somebody unlock an engineer who needs to you become allied with some faction or other.
It turned out that there was only one orbital platform in the system that was giving out the missions required to achieve this.
And every time we showed up to take/hand-in a mission, there was this bloody Python sitting on the only medium pad.
As a result of this, every time we completed a mission, he had to hop into Solo to hand in the mission.
This was a bit frustrating, too, because it meant I couldn't easily discuss which missions he should pick next.
In the end we adopted a "system" where we'd arrive at the platform, I'd go into Solo first, dock, take a quick look at the mission-board, go back into Open, discuss with him which missions he should pick if he gets them and then he'd go into solo, dock, hand in his missions, take more and then go back into Open.
The only "good" thing about it was the same instancing mechanics that caused this Python to continually appear in our instance meant that we almost always ended-up in the same instance of open as each other as well.
Presumably, there weren't a lot of ED players in the area so the game just spawned a single instance every time.