Yeah that's more my line of thinking. Have a job ready but ask for a promotion without revealing that you have an offer. If they promote, great. If they don't,

Yeah that's more my line of thinking. Have a job ready but ask for a promotion without revealing that you have an offer. If they promote, great. If they don't, just leave. If they delay or waffle over the decision, leave. The delay tactics are to pressure the employee psychologically to reveal that he/she has an offer and needs to know about a promotion decision by such and such date. Also it's a good idea to do this around the time of the company's annual review/promotion period (it's not easy to have perfect timing but good to try).