I generally clean my lines every couple of trips by casting as far out as I can, then clean it as I reel back in. Then about twice a year I pull everything off and give my line a good cleaning. While I'm at it, and have everything ready, I'll go ahead and clean my rods, too. With the Zipcast. It won't hurt my lines, and leaves a nice gloss on the rods.
I figure, if having it on one of the surfaces makes line shoot better, why not put it on both?