If you have a design on your wing, you can cut it out of the protective film rather than taking it off and re-masking it.
thats what I do.
Just did one for TD and the rear wing design was a bit mental (maybe Adam has a pic of it), but using the protective film it was really easy to do. No washing needed either, as the surface hasn't come into contact with any release agents.
Try it, it works.
If only they could mould the shell with the protective film inside the shell. Then laying down masks would be a thing of the past.