Dano solved this for me 9 months ago - read my original post:
What was said then has been repeated in this thread too, but incase anyone wants clarification.
once you have written the first variable - duplicate it 4 more times, then edit each in "guessing pattern" to the following - keep the "source format" as is (%title%):
%artist% : %title%
%artist% / %title%
%artist% - %title%
%artist%-%title%
That should pretty much cover all the bases.