I'm running a group of 6 PC's through HotDQ. All of them are new to 5e and we just started, so the combat is pretty slow, and some of them aren't all that excited about combat to begin with. I'm doing what I can to reduce the number of fights, teach them to roll attack+damage at the same time, etc.
However, one of the other pieces of advice I've heard is for me as the DM to have all NPC's of a given type (e.g. kobolds) go at the same time. I'm using FightTracker so I'm already not wasting a lot of time on figuring out who goes next, but having them move and attack basically as a unit would indeed be even faster.
However, it seems to me that this would be extremely swingy as far as initiative rolls; 8 kobolds going before 6 PCs is a very different fight from 8 kobolds going after 6 PCs. I've thought about having them use "passive initiative" aka take 10 - so presumably they would be roughly in the middle every time, which doesn't give them a clear advantage or disadvantage, though it does seem both a little less realistic and a little less fun than rolling.
How have others handled this, and how did it work out? Does it affect the balance as much as I think it might to consolidate enemy initiative this way (either rolling, or using the average), or am I missing something?