Why the big difference between the 10 and 12k? I’ve run each distance, although 10k and 12k only once, and I’d have to say 8k, 5k, 12k, 10k. I think the course makes a big difference. The 12k was 6 basically pancake flat 2k loops, but the 10k was 2 hilly 5k loops. The 10k was brutal.
I’ve never ran 12k, but that would require a whole different gameplan.
None-the-less I would prefer 12k, 8k, 5k, 10k.
The 10k XC distance in college was brutal. Stick a fork in me.