Allowing 5 TPKs to happen is a DM's problem, not the players' no matter the circumstances. That's because TPK means every single character was killed five times. I cannot imagine that the players are at fault if not even a single pc ever escaped. That strongly suggests to me it's the DM's doing.
Almost all of my campaigns have featured a TPK at some point (usually at the beginning). One TPK is generally fine and can happen in the best of games. I could see a second TPK happening, if the players are acting stupid, but five? No way.
Likewise having lots of 'almost' TPKs is fine and something I'd consider to be nothing more than a sign of a particularly tough camapign. My 3e campaign was like that in the high levels: There was rarely a session _without_ someone dying and frequently there were more than one dead pc in an encounter. But even if they effectively 'lost' an encounter, there was always someone able to get away.
Almost all of my campaigns have featured a TPK at some point (usually at the beginning). One TPK is generally fine and can happen in the best of games. I could see a second TPK happening, if the players are acting stupid, but five? No way.
Likewise having lots of 'almost' TPKs is fine and something I'd consider to be nothing more than a sign of a particularly tough camapign. My 3e campaign was like that in the high levels: There was rarely a session _without_ someone dying and frequently there were more than one dead pc in an encounter. But even if they effectively 'lost' an encounter, there was always someone able to get away.