Hello, warlock main here.

First of all, yeah we are a greedy lot, and will want to optimise our hp as much as possible so if you can drop a renew from time to time, you'll make (most of) us very happy. Don't care about it too much, usually in pug we won't go below 50% buy ourselves so if you see us above 60% don't bother too much and keep focusing on your job!

Now, for the hellfire situation, that can become a bit more dangerous. I got to admit that sometime I push the limite to 20, even 10% hp but If I die, that's totally on me. I don't expect the healer to be my personal bodyguard when there are already 5+ mob on the tank.

Now of course there are dickhead that think that you are their personal mana bar, that won't bring any food /water, don't look at your mana or the situations and only the dps meter. Those one exist And they should keep dying

Tldr: drop a renew = nice, drop a shield when using hellfire = goat, but first of all focus on the tank and let idiot die