[icey]

As an employer, the flipside of this is that there needs to be some value in having someone there that you know is leaving. If someone has been halfway checked out because they've been interviewing elsewhere, it might not be worth keeping them around for six weeks. They can't start any long-running work, or anything with any dependencies, and many people's work quality drops significantly after putting in their notice.

It's a nice idea, for sure; but most jobs can be transitioned in 2 weeks. Anything longer than that and all sense of urgency is lost ("We can transition that in a month", etc).

I've quit both ways -- with a long notice period and a short one, and short notice periods are the only times that there's been an actual transition plan.