I think there were 4 teams in series 4 that got to level 3. Considering there were only 8 teams in the series this is impressive. I don't think there were any level one deaths at all either, and most of the level 2 deaths were toward the end of the level.

Perhaps it was an easier series because series 3 had been so hard? Or perhaps there were just great teams.

And in series 5 as you say only 2 people got to level 3, which seems to imply level 2 was tricky.

I think they must have thought level 2 in series 4 was too easy, so increased the difficulty of level 2 to make it harder. This might account for the reason that only two teams reached level 3 in the fifth series. Hope that makes some sort of sense.

Agree with everything you say except the series which has just been on level 1 was not easy two was tricky.

In past series they also went over the top with the lifeforce meeter sometimes they could of only worked through two doors & life force would be low.

Perhaps it was an easier series because series 3 had been so hard? Or perhaps there were just great teams.

And in series 5 as you say only 2 people got to level 3, which seems to imply level 2 was tricky.

I think they must have thought level 2 in series 4 was too easy, so increased the difficulty of level 2 to make it harder. This might account for the reason that only two teams reached level 3 in the fifth series. Hope that makes some sort of sense.