We were discussing the same thing today about our recent Friday session - "5km pace" feels damn fast and "3km pace" feels like an all-out effort over 300m. Back in 'the day' I never ever managed to run 1km reps at my 5km PB (3.08) pace and I only ever managed to run about 3 at my 10k PB (3.14) pace. Even with bulk recovery. Just a race thing...
Loose gravel and rocks don't help either. I don't actually expect to run close to my goal pace (3.24) for the 5000m on Sunday anyway.
Fairly large gap between 52 (3.12 pace) and 60 (3.42 pace). I would have expected you to be more consistent. Suggests the surface is pretty bad or the measurement is out.
Tooms - definitely psychosomatic. Looks like you needed a coach screaming at you and running partners just ahead on the intervals.
It wasn't flat, half in each direction, I didn't always start and finish at exactly the same point and most were more accelerations than hard efforts so I'm not really taking that much notice of the pace. I'm sure I was going sub 3 pace at the end of some efforts.