Kind of reminds me of the system we used in my band in the 90s: The person who brought the initial idea to the band gets to be first. After that, it was based on importance of contributions as determined by myself as the benign dictator, but if I contributed, my name always came last (unless I was the one who brought the idea to the band).
This is exactly how most professors and managers do it. Unless they themselves do the majority of the writing they are last by convention so it actually has some prestige to be last.
What you don't want is second-to-last on a paper w 4 or more authors. That's the worst.