Any sort of fiction has a limit on the number of characters that the audience can keep track of. For television, the strictures are even tighter, due to budget and the available time for characters to be on screen. This commonly results in much smaller numbers of people than would actually be required to do the task at hand, but at the same time it's usually not that hard to make it work.
Think of any of the Star Treks, for example. Out of hundreds of people on the Enterprise and three watches required to keep the ship going, the audience basically only sees the bridge officers of the first watch and the first watch medical staff, especially in the original series. And when there's a new planet to be explored, the senior officers troop off the bridge down to the transporter room to do it, including and especially the captain! How likely is that, actually? Not likely at all, but it was necessary for the story mechanics and the budget, and it worked. And when bad things happened, they were usually the simple peril of adventure fiction, and even then, the writers took care to note that there was a lot of dead time between episodes. Routine missions, or simply time in transit; either way, it gives the crew time to relax and recover and enjoy normal routine with friends.
Torchwood has a small group for similar reasons, but that's where the similarity stops. The team aren't friends with each other — the writers seem to take pains to hammer on that point again and again — and if they have any friends outside of work they can't talk about what they're going through. The bad things are really bad, and only in episode eight do we get the very first hint that the first seven episodes weren't back-to-back; apparently it's been three months, so instead of another day, another horror, it's more like another week, another horror. I'm not sure that's much help. It still seems like a job that is guaranteed to kill you one way or another, probably sooner than later.