Originally Posted by Mraktar

Why 12-5 (40 st) and 12-3 (35 st) and not 12-1 (33 st)? Is there increased chance of ampies or something else that i don't know? i'm interested in this answer too.
1-3 is good only for exp grind, but 12 chapter has ampies in loot.

All the stages in Mission 12 can give ampies. 12-1/3/5 were the ones most often run for varying reasons, 12-1 for pure ampy farming (best stam:ampy ratio), 12-3 for more exp than 12-1, and 12-5 for more exp/gold/seeds. 12-2 and 12-4 gave less gold than 12-1 and had worse RNG than the other 3 stages.