Just a thought about reving....

First of all, THIS IS SITUATIONAL.
I've done a lot of runs with random parties, and what I often see is that people get impatient if you don't rev them. There has been many times where I was the last one left standing, with two or three bars of health left and a few hearts sprinkled in the area and a few monsters I could kite. Personally, I would NOT immediately go rev a team member in this situation, because one person with some health is often more useful than a couple of people with only half a bar.
This is just my own opinion, feel free to comment.

Because of sonic mode/last stand effect, having having two or three bars of health is the same as having slightly more than 1 bar. Might as well share the rest with others.
One person with some health is NOT more useful than a couple of people with only half a bar. It is equally bad situation to be in.

Misten has it right; the best thing to do with your three hearts is rev someone; then both of you have two hits left, then grab a heart and rev someone else. Then you have three people, each who can take two hits, as opposed to just yourself with 3~4 hearts, who can still only take two hits. Overall party survival increases with the most "hits" between the group, and the last heart rule keeps that number at a constant when you're at low health.
However, I also understand the important of making sure you don't die trying to rev them, and have to agree that some people are simply impatient. Generally, the rule should be to spectate the survivor and watch them, see where the hearts are for them and what they're doing. If it looks like they're kiting, grabbing hearts and circling for revs, there should be no problem. The issues should only come up if the survivor just sits back in a corner and tries to one-man-army everything. That's the kind of person that introduces party wipes, and has no place in any respectable team.

>because one person with some health is often more useful than a couple of people with only half a bar.
I beg to differ!
A monster hit will leave you at 1 pip of health generally on the worst case. So a person with 3 bars of health gets 2 hits. If the same person however revs a teammate, you have 2 people with 3/2 health each, able to get hit two times each.
If you have 1 healthbar, you get two people with 1/2 health, which is the same situation as above but with less hits.
If you have a lot of health, who cares.
Also having more people means enemy aggro gets divided if there are multiple enemies, so also good.
Only case you wouldn't want to rev someone fast is if they are awful at the game I guess?
I agree but you have to put yourself in their shoes. They don't know of you skill/capabilities. They might think you are reckless and don't want to lose to someone who 1. Might be being selfish. 2. Might make them all lose. 3. or is a plain jerk face.