I've never given less than a month's notice, and the notice has always been tied to the end date of whatever project or current workload I happen to have. My direct bosses have always expressed appreciation for this, but then again, I've only ever left a company once because I was dissatisfied working there.

Culture and relationships are a two way street, and you are always responsible for your own part in building it. You might have a shit boss or work for a shit company and it's not going to end well, and if that's the case and there's nothing you can do, then all that's left is to look out for yourself. I wouldn't ever advocate for that to be the default position, though.