I burn it till it's black. Then I burn it some more. I never do juice burns though. I just don't see the need to.
I'm doing strictly the opposite. I only juice burn. I don't see the need to scorch it.
The way I see it, the only real oxidation needed is directly between the coil and wick. As long as the coil don't conduct electricity to the wick, there is no need for any more insulation/oxidation. The little juice burning I do is mainly to get rid of finger grease from rolling, and to make the initial pulsing a little bit easier on the battery.
... not trying to be a smart-.... All roads lead to Rome
Edit: I believe different amount of pre-oxidation is needed for regulated or mech devices. With a mech, you can pulse easier on a wick with less oxidation. Do make sure a good battery is used tho... the resistance of the assembly can be
very low before a layer of insulation is built.