Ok, a little laser theory for you to clear up a few misconceptions.
The laser pot adjusts the current that reaches the laser, this is like a little light, the more current it gets the brighter it shines.
The laser light is reflected off the disc and picked up by the pickup, if the disc has a pit, the light does not reflect, if there is no pit, it is reflected back. Constantly reading the 1's and 0's reflected back from the disc creates the data used by the console.
Burnt DVD's are less reflective than pressed discs, this is due to pressed (original) discs using a silver reflective surface, whereas burnt media uses a purplish dye (usually) which does not reflect the laser back as clearly.
The laser's power on the Wii is turned down so it has quite a weak light, this added to the poor reflectivity of burnt discs causes the pickup to not pickup the pits on the disc properly. This causes the DRE errors.
Someone mentioned that this was a temporary fix for PS2's, this is not the case with the Wii. Lasers do start to fade after a while, if your console is quite old and the laser is starting to fade, then a bodge to revive the laser is to turn the power up. This is only a temporary solution, as the laser is in the process of dying and you can only turn its power up so much before it eventually gives up.
Wii lasers are brand new, and so, full of life, it's just that they do not enough current to reflect back correctly from burnt media. Adjusting the Wii laser is not a temporary solution, it's permanent. Make the laser a little brighter and burnt media will be detected properly.
You can put to much current through a laser, which will shorten it's life, hence the adjustment of 1/16 of a turn and try a disc thats giving you errors, if this does not work try another 1/16th of a turn.
If after a couple of turns there is no improvement, you could be turning the laser pot the wrong way making the laser actually dimmer. Go back to the original position and try the opposite way.
Hope this clears up people misconceptions.