"Life and business are full of choices, and the conventional wisdom is always wired to benefit employers and to make life easier for career coaches, who just love simplistic edicts and soft pablum.  So let’s explore deeply the hard choices for your benefit. I won’t let you off the hook — but not for the reason people might think.

You’re asking me for permission to do something that is bad form and bad business practice. I can’t give you that permission — you must decide whether to do it.

You’ve put a new spin on giving notice. Having had one job offer rescinded, you don’t want to risk it again. You want to actually start a new job before you resign the old one — and this hedge against disaster makes giving notice virtually impossible. Let’s distinguish between what’s allowed, what’s bad, and what’s advisable."

That is very well said.