How long is the master looter range?

In retail there is a set range on how far away the target can be before they are ineligible for loot. Is this also true for vanilla? If so, what is this range? I'm farming Maraudon for money and thought I'd make some extra by letting a rogue/warrior have the blackstone ring, can they just stay at the beginning or do they have to follow me all the way to princess?