For this particular person, the inordinate factor is not the frequency of flights, but the distance: 40 flights in 2019, mostly from the US to Austria via Frankfurt. Now, there are some jobs that really do require such travel (though the business should probably consider hiring locally even though it might be more expensive?), but probably fairly few. The individual doesn't show flying stats after 2021, but presumably the work did get done even in the pandemic years when they couldn't fly as often.