Compared to the rate a which some cosmic Santa Claus would have to be pouring a human-compatible atmosphere onto Mars in order to (say) provide a human-friendly

Compared to the rate a which some cosmic Santa Claus would have to be pouring a human-compatible atmosphere onto Mars in order to (say) provide a human-friendly surface pressure within 1,000 years, a few kilotons of loss per year is not even a rounding error. Figure that you gotta have five-ish psi for people. (Top of Mt. Everest, roughly.) In Mars' lower gravity, you'll need 12.5 pounds(mass) of air per square inch, pressing down, to get that. So about 10 tons per sq. meter...vs. Mars has a radius of ~3,400km.