This is perfectly fine although according to reports from the MacRumors forums, users are claiming that when using a full-device skin with the Jet Black iPhone 7 model, it can cause the regulatory labels on the phone to peel off. As you can see in the photo to the right, it shows how the label has peeled off from the phone and transferred itself onto the skin.
It doesn’t even have to take long as one user claims that they left the skin on for a minute and after that the labels came right off. It does not seem to be a problem with the skin itself but rather the Jet Black version of the iPhone. Owners of the other color options have not reported anything similar happening.
The Jet Black option is a bit finicky as Apple themselves have acknowledged that due to the design, it is prone to scratches. Even Apple’s manufacturers are apparently having a hard time producing that particular model. In any case the good news is that it doesn’t seem to affect all the Jet Black models, but if you are considering it, then maybe using a full-device skin might not be the best idea if you’re trying to preserve the finish of the phone.