@tinysilverstar: Actually it's both right and wrong; what happens is that the surface layer will harden (important if you can't have the tacky nail polish on the surface as you're going about) but the inner layers will dry slower because the solvent can't evaporate as easily. However, if you paint in thin layers, the entire layer will harden up immediately, so for just using a thin coat rather than a thick coat (which AFAIK most Japanese brands are formulated to be thin), this method works just fine. Similarly, if you are doing a topcoat over nail art that you need to harden immediately, without disturbing the nail art (since the solvent can make it streak or bend), doing a quick-hardening process like this can be beneficial there as well. Obviously if you have the time to spare, using a quick-dry topcoat and applying it properly is going to be for the best.