Clear frame protection tape on rear wheel well (where gunk and grit gets tossed, also once picked up a big nail with my rear tire which scracthed the inside, fork bridge, downtube, chainstays and cable rub spots. Gravel bike has the same treatment.
Mybe excessive, but I occasionally do a bit of gravel on my road bike and some of the tertiary roads have pebbles and so on on them which can get flung up now and then. The tape does protect and weighs next to nothing.