One thing to note:

Time spent gathering preps is often (but not always) also time spent doing other things. Like looking for people to kill. If I know I'm going by an area w/ some prep on my way to some other area that I want to check to see if some enemy is there, and the prep's easy to get, then I'll go ahead and grab it. Because why not?

There are also situations where I'd say it's reasonable for someone to flee/quaff at ~80-90% health. Not a ton, but they exist. Usually situations where in order to have a reasonable chance at killing your opponent you need to land some initial skill (e.g. assassinate, sleep, etc.), you missed it, and nw you're outmatched in melee to the extent that you might get permalagged all the way from "small wounds" to "dead". In situations like that there's little reason to stay. You're almost surely not going to kill your opponent and the longer the stay the more likely you are to die. You had your shot and you missed it; live to fight another day.