The wet-mix is when you blend 2 colors or more on the sponge and here 1-coaters/2-coaters are the best (in my opinion) unless you want to use undies (like white polish). The advantage here is that the colors usually blend very well on the nail and the disadvantage is that you start from zero and makes everything in one go with some slightly longer drying time.
The wet-on-dry is when you already have a manicure in any color and add one color on top of the old one to extend and update an existing manicure. Here I prefer shimmers or polishes with a thinner formula (i.e. not 1-coaters) and a disadvantage is that the two colors actually don't blend, it's just one polish being layered ûber thin to make it look like if it's blended and sometime this takes a lot of time to achieve well. The huge advantage is that it can update an old mani in a simple and mostly a very quick way. Below is a manicure which is wet-on-dry which I probably could have blended way better. However from a distance it looks really cool, it's just two polishes and still a "middle" color appear. :)
|Had to show you with sunshine too. The shimmer really shows then.|
HM - Blue My Mind
If you managed to go through all my text above, which method do you prefer? Depending on the polish both can create the same result with the same ease in my opinion. So based on that I actually prefer both methods equally depending on the time and what I want to create. :)