A unit skilled in entertainment, mining, and working arrives in
a locale never before visited. This unit should be able to look
around and determine which of its skills will earn the most per
unit time, within reason. The way this worked before, the unit
could entertain for a week only to find out that it had earned
zero income.
Most of my thoughts on this subject range into feature specific areas of
the game and I think Rich's request is more just, in general, is some
small variation good or bad. I'd say SMALL variations are OK and require
no justification. Anything more than a few percent variation should be
somewhat rational and predictable.