Shouldnt they at least track where the bandits are going while sending someone to the other army to maintain communications somehow?
Or the author might just have the bandits camp out somewhere and they just ambush them during the night.
Maybe what the rock decides to be valuable depends on the people around it?
Thats why you only had rohans cash and the diamond earlier in the villa, and when they were in the jungle you only got the diamond and Rohan's sketch moving towards it.