You need to collect food, do you go to where you know there are berries (low value but high likelihood of finding), or scout off to find a herd of deer? (High value but low likelihood of finding).

Looking for deer wouldnt be walking off in a random direction. You check water holes, known clearings, known fields.

Each of these is an operation (walk to X and look), each has a low probability of meeting a deer.

This is a variable reward scheme.

The result is optmize foraging practices - you mostly hunt for deer then fall back to berries. In larger groups some will gather berries some will hunt.

Contrary to popular thought hunter and gatherer were not separate occupations.