One roll per side - but I'm playing an older edition of the game where that is the rule.
This is how we played from about 1986 until around 1996. And while I'm not *certain* I think it fostered teamwork. Since the players all acted at the same time, they tended to organize their actions.
But that took longer. Because they sat around for sometimes half an hour talking about what the best thing to do was.
But it was more fun, I think. Since the players felt like they were working together.
Nowadays it feels like being on offense in baseball. When it's your turn, it's your job to basically hit the ball as far as you can, with some rare tactical exceptions. There's no sense of strategy.
Whereas it used to feel more like being on defense--or really either side--in Football. We think the enemy is going to do this, here's what we're going to do to stop them.
One problem I had playing a Warlord was that it only worked as advertised if the players were willing to sacrifice maximizing their short-term solo effectiveness, in order to maximize the group's long-term effectiveness.
In other words; we'd be fighting a lot of Undead of different roles. One of whom was a Leader. The Leader was buffing all his mans, keeping everyone alive. Or rather, "alive."
I said "We need to stop that dude, otherwise this battle will take forever and we'll blow all our resources." I lay down all my cool enemy debuffs and PC buffs, but on each player's turn, he'd almost always just focus on the bad guy in front of him. Even though the bad guy in front of him was almost unkillable because of the Leader.
"I can't attack the leader," they'd say "because then I'll take an attack of op from this dude."
Well, yes. Yes you will. That's the sacrifice, that's the price we pay in order for the group to achieve together what it couldn't do when each man acts alone.
Otherwise, if each player on his turn looks at the guy in front of him and makes his decision based on how to maximize damage to that bad guy, there's no need for or benefit from a PC Leader. Other than healing.