all these years, I was told that it is a professional courtesy, one that is expected, for an employee to give two weeks notice, at the least...and for more senior management, an even longer notice was expected, primarily to ease the transition...looks like things have changed in the business world...
but as for the topic...people DO quit their bosses, moreso than their companies...
on the other hand, for the good of the company, some people should be terminated immediately...