From leveling Astro today in Holminster Switch - first run WAR, he sniped most heals he would need, DPS took more damage, few vuln stacks but nothing major. Lots of gravity and a nice run... Second run sprout WAR tank - gets instantly deleted on first pull, gets 4 vuln stacks at first boss, has to be babysit on trash pulls as he barely hits his heals or mits if at all. Dohn Mheg Pala - does first pull, melting like candy, had to spam heal but aside from that it's chill, everyone knows what to do. 4-mentor Switch - hard chill... and 2 casters so the red card is meh :P
Had Tender Valley run when the last boss didn't even started the blob mechanic... or a 4-mentor run in which we even managed to screw up arrows
The problem is that the variety is extremely high and the game "has to" support it. The game assumes that it's "fine" that you are in SHB and don't know how to wall pull with heal and mit as WAR... And in Dawntrail they only added "have a one-shot if you don't know the thing" which isn't much (and it's vastly easier to KO a healer than even a noob tank).