I bought a large roll many years ago. First thing I did was run a strip along the roof edge where it rolls over the side just for added protection. Has come in handy as I have had limbs drag and the tape takes it well.
I used it to secure and seal a vent cover that I found in the dumpster without the attachment hardware. Has been up there for about five years. Just taped it to the roof and it works great.
Have used it to secure the antenna wire to the roof.
Have used it to seal the hole for the external cell antenna cable.
Have used it to seal the hole I punched through the sidewall with a screw that was too long... just a little square and you can barely see it.
I put a layer on the roof under the roof pod mounts to keep them from wearing through the roof rubber.
I keep a little in the RV for emergencies as well. Comes in really handy for all sorts of things as it is very sticky!