Is there a standard or convention for what 'counts' as a low orbit for other solar system bodies?
I'm currently writing code for computing arbitrary Hohmann/ patched conics transfers, and I am looking for a streamlined way of calculating what a Low Orbit ought to be, given an object's size, atmospheric height, etc.. To maximise the Oberth effect, the periapsis of any orbit must be as low as possible, but not too low as to fall foul of local mascons or experience an unplanned high-speed rendezvous with the atmosphere or mountains. That suggests a low orbit 'sweet spot' for such calculations.
Earth's low orbit (LEO) is given as a range from about 200 km to 2000 km. The lower boundary is limited by atmospheric drag and the time the satellite is expected to remain in orbit. The upper boundary seems more or less arbitrary from what I can read.
On this delta-V map, the author gives some standard 'low orbits' for various celestial bodies. These range from 100 km for the Moon and the moons of Jupiter, to 250 km for earth, 400 km for Venus, 1000 km for Uranus, Neptune and Titan and 2000 km for Saturn and Jupiter. I think these numbers are generally reasonable, but it's also clear that they are somewhat arbitrarily chosen.
What is a reasonable heuristic for choosing a low orbit radius, based on the size and atmospheric height of the target planet?