In my experience I would say no. I sanded my work until the seams were as smooth as I could get them. After that, I used a cloth buffing wheel in my Dremel tool to smooth the plastic and seams-turned out like glass! Then I would apply the foil and never had a problem. Although it is thin, Reynold's Wrap does have a thickness to it and so far seams and blemishes have not surfaced.
I'll add one more technique for the brave-after putting a piece on, if you gently removed it the foil will get really small wrinkles in it. If you then put it back and lightly smooth it out, it really looks like the stressed skin of a WWII plane. I found this out by accident but was already almost done and there was no way I was going to start from scratch! :)
Rick