Yea, maybe it isn't necessary, but it's always better to do it, than fit it with a slim chance it isn't sealing properly. I had 3 speedvision mani's (not just for myself
) and when you put them on a flat surface, there not completely flat. One of them was mounted last week (and the owner was to lazy to skim it) and didn't seal. Also seen it with other brands like japspeed and silk road.
Ok, if you buy that cruise mani, they do it at the factory, but that is more than 6 times the price of these autobahn items.
If you want something like this to have the same quality as a mani of a thousand bucks, you're just another guy how wants something cheap for half the price
So don't complain, and skim it yourself with a glass plate and some sanding paper