They aren't always accurate, to be honest.

I gave EX6 a try a few times myself last week - haven't completed it yet though.

One of the parties I joined was clearly 'advertised' as a Practice run, however some of the party members took offense at my admittance that I was new, and inexperienced, where this trial was concerned. Though have to admit that I, at that point, hadn't watched the apparently essential "Hector guide"*. In view of this I opted to leave, and I was clearly not wanted and was hesitant about doing it in the first place!

*I've since watched said guide and to be honest, it didn't really help as I don't tend to be able to memorize what I see in guide videos.