Not too often. The Genesis doesn't seem to consume much, so maybe halfway through a 6k mile OCI.
The Jeep burns nothing, just changed the oil last weekend after a 4,900 mile 27 month OCI. I think I checked it once in over 2 years. Was uneventful.
The Camry smokes on startup from the valve guide seals, burns a quart every 2,500 miles or so. Surprisingly it doesn't burn that much given the smoke plumes.