Quarterly or thereabouts I’ll wash mine properly, then clay it and seal it with something that doesn’t leave white residue on black plastic. Lately using Meguiars Ultimate Fast Finish.
In between I’ll use just a pressure washer or a touchless car wash. It’s my thinking the best way to protect the paint is to avoid rubbing dirt into it, which is why I literally don’t touch it between doing a complete reapplication of sealer.
For the same reason, I never use polish, buffers, or anything abrasive that will thin the clearcoat. If it gets a scratch, it’s gonna stay there. If I ever break out polishing compound, I’m getting it ready to sell
I’m less concerned with a bright and shiny everyday appearance than I am with long term preservation of the paint.