And organise by team too, if there is enough on each.
Of course, if you're doing it during work then you don't have the luxury of time and just jump into the public, but during weekends when you have time to coordinate it is indeed to spread out the groups.
For moltres I raided in a group of 4 and I sent in a group of 'rubbish' (gyarados, vapes) and deliberately let them all faint (there's no way 6 mon sustain the whole battle with 4 people), then let the autoselect get my golems and resumed, I still managed to get 3 balls for damage.
Whereas if I go into a 15+ lobby and use my golems in the beginning, I get like 1 ball for the damage bonus even if I don't go out and come back in.