I've just added the following to [[WP:3RR]]. I think it concisely reflects how these things actually work. Feel free, of course, to edit ;-)
I'm a big fan of 3RR blocks, because sterile reverting is bad. But if someone emails me acknowledging their error and asking to be unblocked, I'll generally do so. The idea is to get people to edit better. Some admins are real hardarses about it, but I'm not sure that's really productive myself.
==I've been blocked under 3RR! What do I do?== First, check if you actually did make a fourth revert in 24 hours or very close to it.
*If you didn't, you should email the admin who blocked you (or another admin), politely point this out and ask to be unblocked. *If you did, you should either wait the 24 hours to calm down, or email the admin who blocked you (or another admin), acknowledge your error and apologise and ask to be unblocked.
Some admins look at the quality of the edits in question, but most admins do not as the rule does not concern itself with edit quality.
Note that historically, public denunciation of the blocking admin has not tended to gain sympathy.
- d.