Are there parts of your car(s) you actually use that tape on? Bumpers, lower parts of the doors? Or would the seam be too conspicuous? For a large piece, unless you cover the whole thing, wondering if after a couple of years the paint might show a "reverse tan line" from fading where there was no tape.
No I haven't used any on this car ...yet. I simply haven't felt I need to; I'm not entering and exiting the car in hobnail boots and don't rest things on the top of the rear bumper as I load through the tailgate, and i don't have a dog to scuff the paintwork on the way in or out of the car.
I do however, polish small scratches out using Autoglym Super Resin Polish and follow that up with a couple of coats of Colinite 845 Insulator Wax - a process I use on the rest of the car too.
As for fading I doubt you'd notice much. The tape if exposed to sunlight for ages, can go yellow - but if it's on the door-sills then hardly any direct light will reach it.
Yes you can see the seams slightly, but if you cut the tape out carefully and make the abutted joins neat it's hardly a showstopper.